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Edit File: immutable.d.ts

/**
 * Immutable data encourages pure functions (data-in, data-out) and lends itself
 * to much simpler application development and enabling techniques from
 * functional programming such as lazy evaluation.
 *
 * While designed to bring these powerful functional concepts to JavaScript, it
 * presents an Object-Oriented API familiar to Javascript engineers and closely
 * mirroring that of Array, Map, and Set. It is easy and efficient to convert to
 * and from plain Javascript types.
 *
 * ## How to read these docs
 *
 * In order to better explain what kinds of values the Immutable.js API expects
 * and produces, this documentation is presented in a statically typed dialect of
 * JavaScript (like [Flow][] or [TypeScript][]). You *don't need* to use these
 * type checking tools in order to use Immutable.js, however becoming familiar
 * with their syntax will help you get a deeper understanding of this API.
 *
 * **A few examples and how to read them.**
 *
 * All methods describe the kinds of data they accept and the kinds of data
 * they return. For example a function which accepts two numbers and returns
 * a number would look like this:
 *
 * ```js
 * sum(first: number, second: number): number
 * ```
 *
 * Sometimes, methods can accept different kinds of data or return different
 * kinds of data, and this is described with a *type variable*, which is
 * typically in all-caps. For example, a function which always returns the same
 * kind of data it was provided would look like this:
 *
 * ```js
 * identity<T>(value: T): T
 * ```
 *
 * Type variables are defined with classes and referred to in methods. For
 * example, a class that holds onto a value for you might look like this:
 *
 * ```js
 * class Box<T> {
 * constructor(value: T)
 * getValue(): T
 * }
 * ```
 *
 * In order to manipulate Immutable data, methods that we're used to affecting
 * a Collection instead return a new Collection of the same type. The type
 * `this` refers to the same kind of class. For example, a List which returns
 * new Lists when you `push` a value onto it might look like:
 *
 * ```js
 * class List<T> {
 * push(value: T): this
 * }
 * ```
 *
 * Many methods in Immutable.js accept values which implement the JavaScript
 * [Iterable][] protocol, and might appear like `Iterable<string>` for something
 * which represents sequence of strings. Typically in JavaScript we use plain
 * Arrays (`[]`) when an Iterable is expected, but also all of the Immutable.js
 * collections are iterable themselves!
 *
 * For example, to get a value deep within a structure of data, we might use
 * `getIn` which expects an `Iterable` path:
 *
 * ```
 * getIn(path: Iterable<string | number>): unknown
 * ```
 *
 * To use this method, we could pass an array: `data.getIn([ "key", 2 ])`.
 *
 *
 * Note: All examples are presented in the modern [ES2015][] version of
 * JavaScript. Use tools like Babel to support older browsers.
 *
 * For example:
 *
 * ```js
 * // ES2015
 * const mappedFoo = foo.map(x => x * x);
 * // ES5
 * var mappedFoo = foo.map(function (x) { return x * x; });
 * ```
 *
 * [ES2015]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/New_in_JavaScript/ECMAScript_6_support_in_Mozilla
 * [TypeScript]: https://www.typescriptlang.org/
 * [Flow]: https://flowtype.org/
 * [Iterable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
 */

declare namespace Immutable {
 /** @ignore */
 type OnlyObject<T> = Extract<T, object>;

/** @ignore */
 type ContainObject<T> = OnlyObject<T> extends object
 ? OnlyObject<T> extends never
 ? false
 : true
 : false;

/**
 * @ignore
 *
 * Used to convert deeply all immutable types to a plain TS type.
 * Using `unknown` on object instead of recursive call as we have a circular reference issue
 */
 export type DeepCopy<T> = T extends Record<infer R>
 ? // convert Record to DeepCopy plain JS object
 {
 [key in keyof R]: ContainObject<R[key]> extends true ? unknown : R[key];
 }
 : T extends Collection.Keyed<infer KeyedKey, infer V>
 ? // convert KeyedCollection to DeepCopy plain JS object
 {
 [key in KeyedKey extends string | number | symbol
 ? KeyedKey
 : string]: V extends object ? unknown : V;
 }
 : // convert IndexedCollection or Immutable.Set to DeepCopy plain JS array
 T extends Collection<infer _, infer V>
 ? Array<DeepCopy<V>>
 : T extends string | number // Iterable scalar types : should be kept as is
 ? T
 : T extends Iterable<infer V> // Iterable are converted to plain JS array
 ? Array<DeepCopy<V>>
 : T extends object // plain JS object are converted deeply
 ? {
 [ObjectKey in keyof T]: ContainObject<T[ObjectKey]> extends true
 ? unknown
 : T[ObjectKey];
 }
 : // other case : should be kept as is
 T;

/**
   * Describes which item in a pair should be placed first when sorting
   *
   * @ignore
   */
  export enum PairSorting {
    LeftThenRight = -1,
    RightThenLeft = +1,
  }

/**
 * Function comparing two items of the same type. It can return:
 *
 * * a PairSorting value, to indicate whether the left-hand item or the right-hand item should be placed before the other
 *
 * * the traditional numeric return value - especially -1, 0, or 1
 *
 * @ignore
 */
 export type Comparator<T> = (left: T, right: T) => PairSorting | number;

/**
 * Lists are ordered indexed dense collections, much like a JavaScript
 * Array.
 *
 * Lists are immutable and fully persistent with O(log32 N) gets and sets,
 * and O(1) push and pop.
 *
 * Lists implement Deque, with efficient addition and removal from both the
 * end (`push`, `pop`) and beginning (`unshift`, `shift`).
 *
 * Unlike a JavaScript Array, there is no distinction between an
 * "unset" index and an index set to `undefined`. `List#forEach` visits all
 * indices from 0 to size, regardless of whether they were explicitly defined.
 */
 namespace List {
 /**
 * True if the provided value is a List
 *
 * 
 * ```js
 * const { List } = require('immutable');
 * List.isList([]); // false
 * List.isList(List()); // true
 * ```
 */
 function isList(maybeList: unknown): maybeList is List<unknown>;

/**
 * Creates a new List containing `values`.
 *
 * 
 * ```js
 * const { List } = require('immutable');
 * List.of(1, 2, 3, 4)
 * // List [ 1, 2, 3, 4 ]
 * ```
 *
 * Note: Values are not altered or converted in any way.
 *
 * 
 * ```js
 * const { List } = require('immutable');
 * List.of({x:1}, 2, [3], 4)
 * // List [ { x: 1 }, 2, [ 3 ], 4 ]
 * ```
 */
 function of<T>(...values: Array<T>): List<T>;
 }

/**
 * Create a new immutable List containing the values of the provided
 * collection-like.
 *
 * Note: `List` is a factory function and not a class, and does not use the
 * `new` keyword during construction.
 *
 * 
 * ```js
 * const { List, Set } = require('immutable')
 *
 * const emptyList = List()
 * // List []
 *
 * const plainArray = [ 1, 2, 3, 4 ]
 * const listFromPlainArray = List(plainArray)
 * // List [ 1, 2, 3, 4 ]
 *
 * const plainSet = Set([ 1, 2, 3, 4 ])
 * const listFromPlainSet = List(plainSet)
 * // List [ 1, 2, 3, 4 ]
 *
 * const arrayIterator = plainArray[Symbol.iterator]()
 * const listFromCollectionArray = List(arrayIterator)
 * // List [ 1, 2, 3, 4 ]
 *
 * listFromPlainArray.equals(listFromCollectionArray) // true
 * listFromPlainSet.equals(listFromCollectionArray) // true
 * listFromPlainSet.equals(listFromPlainArray) // true
 * ```
 */
 function List<T>(collection?: Iterable<T> | ArrayLike<T>): List<T>;

interface List<T> extends Collection.Indexed<T> {
 /**
 * The number of items in this List.
 */
 readonly size: number;

// Persistent changes

/**
 * Returns a new List which includes `value` at `index`. If `index` already
 * exists in this List, it will be replaced.
 *
 * `index` may be a negative number, which indexes back from the end of the
 * List. `v.set(-1, "value")` sets the last item in the List.
 *
 * If `index` larger than `size`, the returned List's `size` will be large
 * enough to include the `index`.
 *
 * 
 * ```js
 * const originalList = List([ 0 ]);
 * // List [ 0 ]
 * originalList.set(1, 1);
 * // List [ 0, 1 ]
 * originalList.set(0, 'overwritten');
 * // List [ "overwritten" ]
 * originalList.set(2, 2);
 * // List [ 0, undefined, 2 ]
 *
 * List().set(50000, 'value').size;
 * // 50001
 * ```
 *
 * Note: `set` can be used in `withMutations`.
 */
 set(index: number, value: T): List<T>;

/**
 * Returns a new List which excludes this `index` and with a size 1 less
 * than this List. Values at indices above `index` are shifted down by 1 to
 * fill the position.
 *
 * This is synonymous with `list.splice(index, 1)`.
 *
 * `index` may be a negative number, which indexes back from the end of the
 * List. `v.delete(-1)` deletes the last item in the List.
 *
 * Note: `delete` cannot be safely used in IE8
 *
 * 
 * ```js
 * List([ 0, 1, 2, 3, 4 ]).delete(0);
 * // List [ 1, 2, 3, 4 ]
 * ```
 *
 * Since `delete()` re-indexes values, it produces a complete copy, which
 * has `O(N)` complexity.
 *
 * Note: `delete` *cannot* be used in `withMutations`.
 *
 * @alias remove
 */
 delete(index: number): List<T>;
 remove(index: number): List<T>;

/**
 * Returns a new List with `value` at `index` with a size 1 more than this
 * List. Values at indices above `index` are shifted over by 1.
 *
 * This is synonymous with `list.splice(index, 0, value)`.
 *
 * 
 * ```js
 * List([ 0, 1, 2, 3, 4 ]).insert(6, 5)
 * // List [ 0, 1, 2, 3, 4, 5 ]
 * ```
 *
 * Since `insert()` re-indexes values, it produces a complete copy, which
 * has `O(N)` complexity.
 *
 * Note: `insert` *cannot* be used in `withMutations`.
 */
 insert(index: number, value: T): List<T>;

/**
 * Returns a new List with 0 size and no values in constant time.
 *
 * 
 * ```js
 * List([ 1, 2, 3, 4 ]).clear()
 * // List []
 * ```
 *
 * Note: `clear` can be used in `withMutations`.
 */
 clear(): List<T>;

/**
 * Returns a new List with the provided `values` appended, starting at this
 * List's `size`.
 *
 * 
 * ```js
 * List([ 1, 2, 3, 4 ]).push(5)
 * // List [ 1, 2, 3, 4, 5 ]
 * ```
 *
 * Note: `push` can be used in `withMutations`.
 */
 push(...values: Array<T>): List<T>;

/**
 * Returns a new List with a size ones less than this List, excluding
 * the last index in this List.
 *
 * Note: this differs from `Array#pop` because it returns a new
 * List rather than the removed value. Use `last()` to get the last value
 * in this List.
 *
 * ```js
 * List([ 1, 2, 3, 4 ]).pop()
 * // List[ 1, 2, 3 ]
 * ```
 *
 * Note: `pop` can be used in `withMutations`.
 */
 pop(): List<T>;

/**
 * Returns a new List with the provided `values` prepended, shifting other
 * values ahead to higher indices.
 *
 * 
 * ```js
 * List([ 2, 3, 4]).unshift(1);
 * // List [ 1, 2, 3, 4 ]
 * ```
 *
 * Note: `unshift` can be used in `withMutations`.
 */
 unshift(...values: Array<T>): List<T>;

/**
 * Returns a new List with a size ones less than this List, excluding
 * the first index in this List, shifting all other values to a lower index.
 *
 * Note: this differs from `Array#shift` because it returns a new
 * List rather than the removed value. Use `first()` to get the first
 * value in this List.
 *
 * 
 * ```js
 * List([ 0, 1, 2, 3, 4 ]).shift();
 * // List [ 1, 2, 3, 4 ]
 * ```
 *
 * Note: `shift` can be used in `withMutations`.
 */
 shift(): List<T>;

/**
 * Returns a new List with an updated value at `index` with the return
 * value of calling `updater` with the existing value, or `notSetValue` if
 * `index` was not set. If called with a single argument, `updater` is
 * called with the List itself.
 *
 * `index` may be a negative number, which indexes back from the end of the
 * List. `v.update(-1)` updates the last item in the List.
 *
 * 
 * ```js
 * const list = List([ 'a', 'b', 'c' ])
 * const result = list.update(2, val => val.toUpperCase())
 * // List [ "a", "b", "C" ]
 * ```
 *
 * This can be very useful as a way to "chain" a normal function into a
 * sequence of methods. RxJS calls this "let" and lodash calls it "thru".
 *
 * For example, to sum a List after mapping and filtering:
 *
 * 
 * ```js
 * function sum(collection) {
 * return collection.reduce((sum, x) => sum + x, 0)
 * }
 *
 * List([ 1, 2, 3 ])
 * .map(x => x + 1)
 * .filter(x => x % 2 === 0)
 * .update(sum)
 * // 6
 * ```
 *
 * Note: `update(index)` can be used in `withMutations`.
 *
 * @see `Map#update`
 */
 update(index: number, notSetValue: T, updater: (value: T) => T): this;
 update(
 index: number,
 updater: (value: T | undefined) => T | undefined
 ): this;
 update<R>(updater: (value: this) => R): R;

/**
 * Returns a new List with size `size`. If `size` is less than this
 * List's size, the new List will exclude values at the higher indices.
 * If `size` is greater than this List's size, the new List will have
 * undefined values for the newly available indices.
 *
 * When building a new List and the final size is known up front, `setSize`
 * used in conjunction with `withMutations` may result in the more
 * performant construction.
 */
 setSize(size: number): List<T>;

// Deep persistent changes

/**
 * Returns a new List having set `value` at this `keyPath`. If any keys in
 * `keyPath` do not exist, a new immutable Map will be created at that key.
 *
 * Index numbers are used as keys to determine the path to follow in
 * the List.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * const list = List([ 0, 1, 2, List([ 3, 4 ])])
 * list.setIn([3, 0], 999);
 * // List [ 0, 1, 2, List [ 999, 4 ] ]
 * ```
 *
 * Plain JavaScript Object or Arrays may be nested within an Immutable.js
 * Collection, and setIn() can update those values as well, treating them
 * immutably by creating new copies of those values with the changes applied.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * const list = List([ 0, 1, 2, { plain: 'object' }])
 * list.setIn([3, 'plain'], 'value');
 * // List([ 0, 1, 2, { plain: 'value' }])
 * ```
 *
 * Note: `setIn` can be used in `withMutations`.
 */
 setIn(keyPath: Iterable<unknown>, value: unknown): this;

/**
 * Returns a new List having removed the value at this `keyPath`. If any
 * keys in `keyPath` do not exist, no change will occur.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * const list = List([ 0, 1, 2, List([ 3, 4 ])])
 * list.deleteIn([3, 0]);
 * // List [ 0, 1, 2, List [ 4 ] ]
 * ```
 *
 * Plain JavaScript Object or Arrays may be nested within an Immutable.js
 * Collection, and removeIn() can update those values as well, treating them
 * immutably by creating new copies of those values with the changes applied.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * const list = List([ 0, 1, 2, { plain: 'object' }])
 * list.removeIn([3, 'plain']);
 * // List([ 0, 1, 2, {}])
 * ```
 *
 * Note: `deleteIn` *cannot* be safely used in `withMutations`.
 *
 * @alias removeIn
 */
 deleteIn(keyPath: Iterable<unknown>): this;
 removeIn(keyPath: Iterable<unknown>): this;

/**
 * Note: `updateIn` can be used in `withMutations`.
 *
 * @see `Map#updateIn`
 */
 updateIn(
 keyPath: Iterable<unknown>,
 notSetValue: unknown,
 updater: (value: unknown) => unknown
 ): this;
 updateIn(
 keyPath: Iterable<unknown>,
 updater: (value: unknown) => unknown
 ): this;

/**
 * Note: `mergeIn` can be used in `withMutations`.
 *
 * @see `Map#mergeIn`
 */
 mergeIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this;

/**
 * Note: `mergeDeepIn` can be used in `withMutations`.
 *
 * @see `Map#mergeDeepIn`
 */
 mergeDeepIn(
 keyPath: Iterable<unknown>,
 ...collections: Array<unknown>
 ): this;

// Transient changes

/**
     * Note: Not all methods can be safely used on a mutable collection or within
     * `withMutations`! Check the documentation for each method to see if it
     * allows being used in `withMutations`.
     *
     * @see `Map#withMutations`
     */
    withMutations(mutator: (mutable: this) => unknown): this;

/**
     * An alternative API for withMutations()
     *
     * Note: Not all methods can be safely used on a mutable collection or within
     * `withMutations`! Check the documentation for each method to see if it
     * allows being used in `withMutations`.
     *
     * @see `Map#asMutable`
     */
    asMutable(): this;

/**
     * @see `Map#wasAltered`
     */
    wasAltered(): boolean;

/**
     * @see `Map#asImmutable`
     */
    asImmutable(): this;

// Sequence algorithms

/**
 * Returns a new List with other values or collections concatenated to this one.
 *
 * Note: `concat` can be used in `withMutations`.
 *
 * @alias merge
 */
 concat<C>(...valuesOrCollections: Array<Iterable<C> | C>): List<T | C>;
 merge<C>(...collections: Array<Iterable<C>>): List<T | C>;

/**
 * Returns a new List with values passed through a
 * `mapper` function.
 *
 * 
 * ```js
 * List([ 1, 2 ]).map(x => 10 * x)
 * // List [ 10, 20 ]
 * ```
 */
 map<M>(
 mapper: (value: T, key: number, iter: this) => M,
 context?: unknown
 ): List<M>;

/**
 * Flat-maps the List, returning a new List.
 *
 * Similar to `list.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: number, iter: this) => Iterable<M>,
 context?: unknown
 ): List<M>;

/**
 * Returns a new List with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, index: number, iter: this) => value is F,
 context?: unknown
 ): List<F>;
 filter(
 predicate: (value: T, index: number, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new List with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends T, C>(
 predicate: (this: C, value: T, index: number, iter: this) => value is F,
 context?: C
 ): [List<T>, List<F>];
 partition<C>(
 predicate: (this: C, value: T, index: number, iter: this) => unknown,
 context?: C
 ): [this, this];

/**
 * Returns a List "zipped" with the provided collection.
 *
 * Like `zipWith`, but using the default `zipper`: creating an `Array`.
 *
 * 
 * ```js
 * const a = List([ 1, 2, 3 ]);
 * const b = List([ 4, 5, 6 ]);
 * const c = a.zip(b); // List [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
 * ```
 */
 zip(other: Collection<unknown, U>): List<[T, U]>;
 zip<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): List<[T, U, V]>;
 zip(...collections: Array<Collection<unknown, unknown>>): List<unknown>;

/**
 * Returns a List "zipped" with the provided collections.
 *
 * Unlike `zip`, `zipAll` continues zipping until the longest collection is
 * exhausted. Missing values from shorter collections are filled with `undefined`.
 *
 * 
 * ```js
 * const a = List([ 1, 2 ]);
 * const b = List([ 3, 4, 5 ]);
 * const c = a.zipAll(b); // List [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
 * ```
 *
 * Note: Since zipAll will return a collection as large as the largest
 * input, some results may contain undefined values. TypeScript cannot
 * account for these without cases (as of v2.5).
 */
 zipAll(other: Collection<unknown, U>): List<[T, U]>;
 zipAll<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): List<[T, U, V]>;
 zipAll(...collections: Array<Collection<unknown, unknown>>): List<unknown>;

/**
 * Returns a List "zipped" with the provided collections by using a
 * custom `zipper` function.
 *
 * 
 * ```js
 * const a = List([ 1, 2, 3 ]);
 * const b = List([ 4, 5, 6 ]);
 * const c = a.zipWith((a, b) => a + b, b);
 * // List [ 5, 7, 9 ]
 * ```
 */
 zipWith<U, Z>(
 zipper: (value: T, otherValue: U) => Z,
 otherCollection: Collection<unknown, U>
 ): List<Z>;
 zipWith<U, V, Z>(
 zipper: (value: T, otherValue: U, thirdValue: V) => Z,
 otherCollection: Collection<unknown, U>,
 thirdCollection: Collection<unknown, V>
 ): List<Z>;
 zipWith<Z>(
 zipper: (...values: Array<unknown>) => Z,
 ...collections: Array<Collection<unknown, unknown>>
 ): List<Z>;
 }

/**
 * Immutable Map is an unordered Collection.Keyed of (key, value) pairs with
 * `O(log32 N)` gets and `O(log32 N)` persistent sets.
 *
 * Iteration order of a Map is undefined, however is stable. Multiple
 * iterations of the same Map will iterate in the same order.
 *
 * Map's keys can be of any type, and use `Immutable.is` to determine key
 * equality. This allows the use of any value (including NaN) as a key.
 *
 * Because `Immutable.is` returns equality based on value semantics, and
 * Immutable collections are treated as values, any Immutable collection may
 * be used as a key.
 *
 * 
 * ```js
 * const { Map, List } = require('immutable');
 * Map().set(List([ 1 ]), 'listofone').get(List([ 1 ]));
 * // 'listofone'
 * ```
 *
 * Any JavaScript object may be used as a key, however strict identity is used
 * to evaluate key equality. Two similar looking objects will represent two
 * different keys.
 *
 * Implemented by a hash-array mapped trie.
 */
 namespace Map {
 /**
 * True if the provided value is a Map
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map.isMap({}) // false
 * Map.isMap(Map()) // true
 * ```
 */
 function isMap(maybeMap: unknown): maybeMap is Map<unknown, unknown>;

/**
 * Creates a new Map from alternating keys and values
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map.of(
 * 'key', 'value',
 * 'numerical value', 3,
 * 0, 'numerical key'
 * )
 * // Map { 0: "numerical key", "key": "value", "numerical value": 3 }
 * ```
 *
 * @deprecated Use Map([ [ 'k', 'v' ] ]) or Map({ k: 'v' })
 */
 function of(...keyValues: Array<unknown>): Map<unknown, unknown>;
 }

/**
 * Creates a new Immutable Map.
 *
 * Created with the same key value pairs as the provided Collection.Keyed or
 * JavaScript Object or expects a Collection of [K, V] tuple entries.
 *
 * Note: `Map` is a factory function and not a class, and does not use the
 * `new` keyword during construction.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ key: "value" })
 * Map([ [ "key", "value" ] ])
 * ```
 *
 * Keep in mind, when using JS objects to construct Immutable Maps, that
 * JavaScript Object properties are always strings, even if written in a
 * quote-less shorthand, while Immutable Maps accept keys of any type.
 *
 * 
 * ```js
 * let obj = { 1: "one" }
 * Object.keys(obj) // [ "1" ]
 * assert.equal(obj["1"], obj[1]) // "one" === "one"
 *
 * let map = Map(obj)
 * assert.notEqual(map.get("1"), map.get(1)) // "one" !== undefined
 * ```
 *
 * Property access for JavaScript Objects first converts the key to a string,
 * but since Immutable Map keys can be of any type the argument to `get()` is
 * not altered.
 */
 function Map<K, V>(collection?: Iterable<[K, V]>): Map<K, V>;
 function Map<V>(obj: { [key: string]: V }): Map<string, V>;
 function Map<K extends string | symbol, V>(obj: { [P in K]?: V }): Map<K, V>;

interface Map<K, V> extends Collection.Keyed<K, V> {
 /**
 * The number of entries in this Map.
 */
 readonly size: number;

// Persistent changes

/**
 * Returns a new Map also containing the new key, value pair. If an equivalent
 * key already exists in this Map, it will be replaced.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const originalMap = Map()
 * const newerMap = originalMap.set('key', 'value')
 * const newestMap = newerMap.set('key', 'newer value')
 *
 * originalMap
 * // Map {}
 * newerMap
 * // Map { "key": "value" }
 * newestMap
 * // Map { "key": "newer value" }
 * ```
 *
 * Note: `set` can be used in `withMutations`.
 */
 set(key: K, value: V): this;

/**
 * Returns a new Map which excludes this `key`.
 *
 * Note: `delete` cannot be safely used in IE8, but is provided to mirror
 * the ES6 collection API.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const originalMap = Map({
 * key: 'value',
 * otherKey: 'other value'
 * })
 * // Map { "key": "value", "otherKey": "other value" }
 * originalMap.delete('otherKey')
 * // Map { "key": "value" }
 * ```
 *
 * Note: `delete` can be used in `withMutations`.
 *
 * @alias remove
 */
 delete(key: K): this;
 remove(key: K): this;

/**
 * Returns a new Map which excludes the provided `keys`.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const names = Map({ a: "Aaron", b: "Barry", c: "Connor" })
 * names.deleteAll([ 'a', 'c' ])
 * // Map { "b": "Barry" }
 * ```
 *
 * Note: `deleteAll` can be used in `withMutations`.
 *
 * @alias removeAll
 */
 deleteAll(keys: Iterable<K>): this;
 removeAll(keys: Iterable<K>): this;

/**
 * Returns a new Map containing no keys or values.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ key: 'value' }).clear()
 * // Map {}
 * ```
 *
 * Note: `clear` can be used in `withMutations`.
 */
 clear(): this;

/**
 * Returns a new Map having updated the value at this `key` with the return
 * value of calling `updater` with the existing value.
 *
 * Similar to: `map.set(key, updater(map.get(key)))`.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const aMap = Map({ key: 'value' })
 * const newMap = aMap.update('key', value => value + value)
 * // Map { "key": "valuevalue" }
 * ```
 *
 * This is most commonly used to call methods on collections within a
 * structure of data. For example, in order to `.push()` onto a nested `List`,
 * `update` and `push` can be used together:
 *
 * 
 * ```js
 * const aMap = Map({ nestedList: List([ 1, 2, 3 ]) })
 * const newMap = aMap.update('nestedList', list => list.push(4))
 * // Map { "nestedList": List [ 1, 2, 3, 4 ] }
 * ```
 *
 * When a `notSetValue` is provided, it is provided to the `updater`
 * function when the value at the key does not exist in the Map.
 *
 * 
 * ```js
 * const aMap = Map({ key: 'value' })
 * const newMap = aMap.update('noKey', 'no value', value => value + value)
 * // Map { "key": "value", "noKey": "no valueno value" }
 * ```
 *
 * However, if the `updater` function returns the same value it was called
 * with, then no change will occur. This is still true if `notSetValue`
 * is provided.
 *
 * 
 * ```js
 * const aMap = Map({ apples: 10 })
 * const newMap = aMap.update('oranges', 0, val => val)
 * // Map { "apples": 10 }
 * assert.strictEqual(newMap, map);
 * ```
 *
 * For code using ES2015 or later, using `notSetValue` is discourged in
 * favor of function parameter default values. This helps to avoid any
 * potential confusion with identify functions as described above.
 *
 * The previous example behaves differently when written with default values:
 *
 * 
 * ```js
 * const aMap = Map({ apples: 10 })
 * const newMap = aMap.update('oranges', (val = 0) => val)
 * // Map { "apples": 10, "oranges": 0 }
 * ```
 *
 * If no key is provided, then the `updater` function return value is
 * returned as well.
 *
 * 
 * ```js
 * const aMap = Map({ key: 'value' })
 * const result = aMap.update(aMap => aMap.get('key'))
 * // "value"
 * ```
 *
 * This can be very useful as a way to "chain" a normal function into a
 * sequence of methods. RxJS calls this "let" and lodash calls it "thru".
 *
 * For example, to sum the values in a Map
 *
 * 
 * ```js
 * function sum(collection) {
 * return collection.reduce((sum, x) => sum + x, 0)
 * }
 *
 * Map({ x: 1, y: 2, z: 3 })
 * .map(x => x + 1)
 * .filter(x => x % 2 === 0)
 * .update(sum)
 * // 6
 * ```
 *
 * Note: `update(key)` can be used in `withMutations`.
 */
 update(key: K, notSetValue: V, updater: (value: V) => V): this;
 update(key: K, updater: (value: V | undefined) => V | undefined): this;
 update<R>(updater: (value: this) => R): R;

/**
 * Returns a new Map resulting from merging the provided Collections
 * (or JS objects) into this Map. In other words, this takes each entry of
 * each collection and sets it on this Map.
 *
 * Note: Values provided to `merge` are shallowly converted before being
 * merged. No nested values are altered.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const one = Map({ a: 10, b: 20, c: 30 })
 * const two = Map({ b: 40, a: 50, d: 60 })
 * one.merge(two) // Map { "a": 50, "b": 40, "c": 30, "d": 60 }
 * two.merge(one) // Map { "b": 20, "a": 10, "d": 60, "c": 30 }
 * ```
 *
 * Note: `merge` can be used in `withMutations`.
 *
 * @alias concat
 */
 merge<KC, VC>(
 ...collections: Array<Iterable<[KC, VC]>>
 ): Map<K | KC, V | VC>;
 merge<C>(
 ...collections: Array<{ [key: string]: C }>
 ): Map<K | string, V | C>;
 concat<KC, VC>(
 ...collections: Array<Iterable<[KC, VC]>>
 ): Map<K | KC, V | VC>;
 concat<C>(
 ...collections: Array<{ [key: string]: C }>
 ): Map<K | string, V | C>;

/**
 * Like `merge()`, `mergeWith()` returns a new Map resulting from merging
 * the provided Collections (or JS objects) into this Map, but uses the
 * `merger` function for dealing with conflicts.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const one = Map({ a: 10, b: 20, c: 30 })
 * const two = Map({ b: 40, a: 50, d: 60 })
 * one.mergeWith((oldVal, newVal) => oldVal / newVal, two)
 * // { "a": 0.2, "b": 0.5, "c": 30, "d": 60 }
 * two.mergeWith((oldVal, newVal) => oldVal / newVal, one)
 * // { "b": 2, "a": 5, "d": 60, "c": 30 }
 * ```
 *
 * Note: `mergeWith` can be used in `withMutations`.
 */
 mergeWith(
 merger: (oldVal: V, newVal: V, key: K) => V,
 ...collections: Array<Iterable<[K, V]> | { [key: string]: V }>
 ): this;

/**
 * Like `merge()`, but when two compatible collections are encountered with
 * the same key, it merges them as well, recursing deeply through the nested
 * data. Two collections are considered to be compatible (and thus will be
 * merged together) if they both fall into one of three categories: keyed
 * (e.g., `Map`s, `Record`s, and objects), indexed (e.g., `List`s and
 * arrays), or set-like (e.g., `Set`s). If they fall into separate
 * categories, `mergeDeep` will replace the existing collection with the
 * collection being merged in. This behavior can be customized by using
 * `mergeDeepWith()`.
 *
 * Note: Indexed and set-like collections are merged using
 * `concat()`/`union()` and therefore do not recurse.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const one = Map({ a: Map({ x: 10, y: 10 }), b: Map({ x: 20, y: 50 }) })
 * const two = Map({ a: Map({ x: 2 }), b: Map({ y: 5 }), c: Map({ z: 3 }) })
 * one.mergeDeep(two)
 * // Map {
 * // "a": Map { "x": 2, "y": 10 },
 * // "b": Map { "x": 20, "y": 5 },
 * // "c": Map { "z": 3 }
 * // }
 * ```
 *
 * Note: `mergeDeep` can be used in `withMutations`.
 */
 mergeDeep(
 ...collections: Array<Iterable<[K, V]> | { [key: string]: V }>
 ): this;

/**
 * Like `mergeDeep()`, but when two non-collections or incompatible
 * collections are encountered at the same key, it uses the `merger`
 * function to determine the resulting value. Collections are considered
 * incompatible if they fall into separate categories between keyed,
 * indexed, and set-like.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const one = Map({ a: Map({ x: 10, y: 10 }), b: Map({ x: 20, y: 50 }) })
 * const two = Map({ a: Map({ x: 2 }), b: Map({ y: 5 }), c: Map({ z: 3 }) })
 * one.mergeDeepWith((oldVal, newVal) => oldVal / newVal, two)
 * // Map {
 * // "a": Map { "x": 5, "y": 10 },
 * // "b": Map { "x": 20, "y": 10 },
 * // "c": Map { "z": 3 }
 * // }
 * ```
 *
 * Note: `mergeDeepWith` can be used in `withMutations`.
 */
 mergeDeepWith(
 merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
 ...collections: Array<Iterable<[K, V]> | { [key: string]: V }>
 ): this;

// Deep persistent changes

/**
 * Returns a new Map having set `value` at this `keyPath`. If any keys in
 * `keyPath` do not exist, a new immutable Map will be created at that key.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const originalMap = Map({
 * subObject: Map({
 * subKey: 'subvalue',
 * subSubObject: Map({
 * subSubKey: 'subSubValue'
 * })
 * })
 * })
 *
 * const newMap = originalMap.setIn(['subObject', 'subKey'], 'ha ha!')
 * // Map {
 * // "subObject": Map {
 * // "subKey": "ha ha!",
 * // "subSubObject": Map { "subSubKey": "subSubValue" }
 * // }
 * // }
 *
 * const newerMap = originalMap.setIn(
 * ['subObject', 'subSubObject', 'subSubKey'],
 * 'ha ha ha!'
 * )
 * // Map {
 * // "subObject": Map {
 * // "subKey": "subvalue",
 * // "subSubObject": Map { "subSubKey": "ha ha ha!" }
 * // }
 * // }
 * ```
 *
 * Plain JavaScript Object or Arrays may be nested within an Immutable.js
 * Collection, and setIn() can update those values as well, treating them
 * immutably by creating new copies of those values with the changes applied.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const originalMap = Map({
 * subObject: {
 * subKey: 'subvalue',
 * subSubObject: {
 * subSubKey: 'subSubValue'
 * }
 * }
 * })
 *
 * originalMap.setIn(['subObject', 'subKey'], 'ha ha!')
 * // Map {
 * // "subObject": {
 * // subKey: "ha ha!",
 * // subSubObject: { subSubKey: "subSubValue" }
 * // }
 * // }
 * ```
 *
 * If any key in the path exists but cannot be updated (such as a primitive
 * like number or a custom Object like Date), an error will be thrown.
 *
 * Note: `setIn` can be used in `withMutations`.
 */
 setIn(keyPath: Iterable<unknown>, value: unknown): this;

/**
 * Returns a new Map having removed the value at this `keyPath`. If any keys
 * in `keyPath` do not exist, no change will occur.
 *
 * Note: `deleteIn` can be used in `withMutations`.
 *
 * @alias removeIn
 */
 deleteIn(keyPath: Iterable<unknown>): this;
 removeIn(keyPath: Iterable<unknown>): this;

/**
 * Returns a new Map having applied the `updater` to the entry found at the
 * keyPath.
 *
 * This is most commonly used to call methods on collections nested within a
 * structure of data. For example, in order to `.push()` onto a nested `List`,
 * `updateIn` and `push` can be used together:
 *
 * 
 * ```js
 * const { Map, List } = require('immutable')
 * const map = Map({ inMap: Map({ inList: List([ 1, 2, 3 ]) }) })
 * const newMap = map.updateIn(['inMap', 'inList'], list => list.push(4))
 * // Map { "inMap": Map { "inList": List [ 1, 2, 3, 4 ] } }
 * ```
 *
 * If any keys in `keyPath` do not exist, new Immutable `Map`s will
 * be created at those keys. If the `keyPath` does not already contain a
 * value, the `updater` function will be called with `notSetValue`, if
 * provided, otherwise `undefined`.
 *
 * 
 * ```js
 * const map = Map({ a: Map({ b: Map({ c: 10 }) }) })
 * const newMap = map.updateIn(['a', 'b', 'c'], val => val * 2)
 * // Map { "a": Map { "b": Map { "c": 20 } } }
 * ```
 *
 * If the `updater` function returns the same value it was called with, then
 * no change will occur. This is still true if `notSetValue` is provided.
 *
 * 
 * ```js
 * const map = Map({ a: Map({ b: Map({ c: 10 }) }) })
 * const newMap = map.updateIn(['a', 'b', 'x'], 100, val => val)
 * // Map { "a": Map { "b": Map { "c": 10 } } }
 * assert.strictEqual(newMap, aMap)
 * ```
 *
 * For code using ES2015 or later, using `notSetValue` is discourged in
 * favor of function parameter default values. This helps to avoid any
 * potential confusion with identify functions as described above.
 *
 * The previous example behaves differently when written with default values:
 *
 * 
 * ```js
 * const map = Map({ a: Map({ b: Map({ c: 10 }) }) })
 * const newMap = map.updateIn(['a', 'b', 'x'], (val = 100) => val)
 * // Map { "a": Map { "b": Map { "c": 10, "x": 100 } } }
 * ```
 *
 * Plain JavaScript Object or Arrays may be nested within an Immutable.js
 * Collection, and updateIn() can update those values as well, treating them
 * immutably by creating new copies of those values with the changes applied.
 *
 * 
 * ```js
 * const map = Map({ a: { b: { c: 10 } } })
 * const newMap = map.updateIn(['a', 'b', 'c'], val => val * 2)
 * // Map { "a": { b: { c: 20 } } }
 * ```
 *
 * If any key in the path exists but cannot be updated (such as a primitive
 * like number or a custom Object like Date), an error will be thrown.
 *
 * Note: `updateIn` can be used in `withMutations`.
 */
 updateIn(
 keyPath: Iterable<unknown>,
 notSetValue: unknown,
 updater: (value: unknown) => unknown
 ): this;
 updateIn(
 keyPath: Iterable<unknown>,
 updater: (value: unknown) => unknown
 ): this;

/**
 * A combination of `updateIn` and `merge`, returning a new Map, but
 * performing the merge at a point arrived at by following the keyPath.
 * In other words, these two lines are equivalent:
 *
 * ```js
 * map.updateIn(['a', 'b', 'c'], abc => abc.merge(y))
 * map.mergeIn(['a', 'b', 'c'], y)
 * ```
 *
 * Note: `mergeIn` can be used in `withMutations`.
 */
 mergeIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this;

/**
 * A combination of `updateIn` and `mergeDeep`, returning a new Map, but
 * performing the deep merge at a point arrived at by following the keyPath.
 * In other words, these two lines are equivalent:
 *
 * ```js
 * map.updateIn(['a', 'b', 'c'], abc => abc.mergeDeep(y))
 * map.mergeDeepIn(['a', 'b', 'c'], y)
 * ```
 *
 * Note: `mergeDeepIn` can be used in `withMutations`.
 */
 mergeDeepIn(
 keyPath: Iterable<unknown>,
 ...collections: Array<unknown>
 ): this;

// Transient changes

/**
 * Every time you call one of the above functions, a new immutable Map is
 * created. If a pure function calls a number of these to produce a final
 * return value, then a penalty on performance and memory has been paid by
 * creating all of the intermediate immutable Maps.
 *
 * If you need to apply a series of mutations to produce a new immutable
 * Map, `withMutations()` creates a temporary mutable copy of the Map which
 * can apply mutations in a highly performant manner. In fact, this is
 * exactly how complex mutations like `merge` are done.
 *
 * As an example, this results in the creation of 2, not 4, new Maps:
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const map1 = Map()
 * const map2 = map1.withMutations(map => {
 * map.set('a', 1).set('b', 2).set('c', 3)
 * })
 * assert.equal(map1.size, 0)
 * assert.equal(map2.size, 3)
 * ```
 *
 * Note: Not all methods can be used on a mutable collection or within
 * `withMutations`! Read the documentation for each method to see if it
 * is safe to use in `withMutations`.
 */
 withMutations(mutator: (mutable: this) => unknown): this;

/**
     * Another way to avoid creation of intermediate Immutable maps is to create
     * a mutable copy of this collection. Mutable copies *always* return `this`,
     * and thus shouldn't be used for equality. Your function should never return
     * a mutable copy of a collection, only use it internally to create a new
     * collection.
     *
     * If possible, use `withMutations` to work with temporary mutable copies as
     * it provides an easier to use API and considers many common optimizations.
     *
     * Note: if the collection is already mutable, `asMutable` returns itself.
     *
     * Note: Not all methods can be used on a mutable collection or within
     * `withMutations`! Read the documentation for each method to see if it
     * is safe to use in `withMutations`.
     *
     * @see `Map#asImmutable`
     */
    asMutable(): this;

/**
     * Returns true if this is a mutable copy (see `asMutable()`) and mutative
     * alterations have been applied.
     *
     * @see `Map#asMutable`
     */
    wasAltered(): boolean;

/**
     * The yin to `asMutable`'s yang. Because it applies to mutable collections,
     * this operation is *mutable* and may return itself (though may not
     * return itself, i.e. if the result is an empty collection). Once
     * performed, the original mutable copy must no longer be mutated since it
     * may be the immutable result.
     *
     * If possible, use `withMutations` to work with temporary mutable copies as
     * it provides an easier to use API and considers many common optimizations.
     *
     * @see `Map#asMutable`
     */
    asImmutable(): this;

// Sequence algorithms

/**
 * Returns a new Map with values passed through a
 * `mapper` function.
 *
 * Map({ a: 1, b: 2 }).map(x => 10 * x)
 * // Map { a: 10, b: 20 }
 */
 map<M>(
 mapper: (value: V, key: K, iter: this) => M,
 context?: unknown
 ): Map<K, M>;

/**
 * @see Collection.Keyed.mapKeys
 */
 mapKeys<M>(
 mapper: (key: K, value: V, iter: this) => M,
 context?: unknown
 ): Map<M, V>;

/**
 * @see Collection.Keyed.mapEntries
 */
 mapEntries<KM, VM>(
 mapper: (
 entry: [K, V],
 index: number,
 iter: this
 ) => [KM, VM] | undefined,
 context?: unknown
 ): Map<KM, VM>;

/**
 * Flat-maps the Map, returning a new Map.
 *
 * Similar to `data.map(...).flatten(true)`.
 */
 flatMap<KM, VM>(
 mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
 context?: unknown
 ): Map<KM, VM>;

/**
 * Returns a new Map with only the entries for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends V>(
 predicate: (value: V, key: K, iter: this) => value is F,
 context?: unknown
 ): Map<K, F>;
 filter(
 predicate: (value: V, key: K, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new Map with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends V, C>(
 predicate: (this: C, value: V, key: K, iter: this) => value is F,
 context?: C
 ): [Map<K, V>, Map<K, F>];
 partition<C>(
 predicate: (this: C, value: V, key: K, iter: this) => unknown,
 context?: C
 ): [this, this];

/**
 * @see Collection.Keyed.flip
 */
 flip(): Map<V, K>;
 }

/**
 * A type of Map that has the additional guarantee that the iteration order of
 * entries will be the order in which they were set().
 *
 * The iteration behavior of OrderedMap is the same as native ES6 Map and
 * JavaScript Object.
 *
 * Note that `OrderedMap` are more expensive than non-ordered `Map` and may
 * consume more memory. `OrderedMap#set` is amortized O(log32 N), but not
 * stable.
 */
 namespace OrderedMap {
 /**
 * True if the provided value is an OrderedMap.
 */
 function isOrderedMap(
 maybeOrderedMap: unknown
 ): maybeOrderedMap is OrderedMap<unknown, unknown>;
 }

/**
 * Creates a new Immutable OrderedMap.
 *
 * Created with the same key value pairs as the provided Collection.Keyed or
 * JavaScript Object or expects a Collection of [K, V] tuple entries.
 *
 * The iteration order of key-value pairs provided to this constructor will
 * be preserved in the OrderedMap.
 *
 * let newOrderedMap = OrderedMap({key: "value"})
 * let newOrderedMap = OrderedMap([["key", "value"]])
 *
 * Note: `OrderedMap` is a factory function and not a class, and does not use
 * the `new` keyword during construction.
 */
 function OrderedMap<K, V>(collection?: Iterable<[K, V]>): OrderedMap<K, V>;
 function OrderedMap<V>(obj: { [key: string]: V }): OrderedMap<string, V>;

interface OrderedMap<K, V> extends Map<K, V> {
 /**
 * The number of entries in this OrderedMap.
 */
 readonly size: number;

/**
 * Returns a new OrderedMap also containing the new key, value pair. If an
 * equivalent key already exists in this OrderedMap, it will be replaced
 * while maintaining the existing order.
 *
 * 
 * ```js
 * const { OrderedMap } = require('immutable')
 * const originalMap = OrderedMap({a:1, b:1, c:1})
 * const updatedMap = originalMap.set('b', 2)
 *
 * originalMap
 * // OrderedMap {a: 1, b: 1, c: 1}
 * updatedMap
 * // OrderedMap {a: 1, b: 2, c: 1}
 * ```
 *
 * Note: `set` can be used in `withMutations`.
 */
 set(key: K, value: V): this;

/**
 * Returns a new OrderedMap resulting from merging the provided Collections
 * (or JS objects) into this OrderedMap. In other words, this takes each
 * entry of each collection and sets it on this OrderedMap.
 *
 * Note: Values provided to `merge` are shallowly converted before being
 * merged. No nested values are altered.
 *
 * 
 * ```js
 * const { OrderedMap } = require('immutable')
 * const one = OrderedMap({ a: 10, b: 20, c: 30 })
 * const two = OrderedMap({ b: 40, a: 50, d: 60 })
 * one.merge(two) // OrderedMap { "a": 50, "b": 40, "c": 30, "d": 60 }
 * two.merge(one) // OrderedMap { "b": 20, "a": 10, "d": 60, "c": 30 }
 * ```
 *
 * Note: `merge` can be used in `withMutations`.
 *
 * @alias concat
 */
 merge<KC, VC>(
 ...collections: Array<Iterable<[KC, VC]>>
 ): OrderedMap<K | KC, V | VC>;
 merge<C>(
 ...collections: Array<{ [key: string]: C }>
 ): OrderedMap<K | string, V | C>;
 concat<KC, VC>(
 ...collections: Array<Iterable<[KC, VC]>>
 ): OrderedMap<K | KC, V | VC>;
 concat<C>(
 ...collections: Array<{ [key: string]: C }>
 ): OrderedMap<K | string, V | C>;

// Sequence algorithms

/**
 * Returns a new OrderedMap with values passed through a
 * `mapper` function.
 *
 * OrderedMap({ a: 1, b: 2 }).map(x => 10 * x)
 * // OrderedMap { "a": 10, "b": 20 }
 *
 * Note: `map()` always returns a new instance, even if it produced the same
 * value at every step.
 */
 map<M>(
 mapper: (value: V, key: K, iter: this) => M,
 context?: unknown
 ): OrderedMap<K, M>;

/**
 * @see Collection.Keyed.mapKeys
 */
 mapKeys<M>(
 mapper: (key: K, value: V, iter: this) => M,
 context?: unknown
 ): OrderedMap<M, V>;

/**
 * @see Collection.Keyed.mapEntries
 */
 mapEntries<KM, VM>(
 mapper: (
 entry: [K, V],
 index: number,
 iter: this
 ) => [KM, VM] | undefined,
 context?: unknown
 ): OrderedMap<KM, VM>;

/**
 * Flat-maps the OrderedMap, returning a new OrderedMap.
 *
 * Similar to `data.map(...).flatten(true)`.
 */
 flatMap<KM, VM>(
 mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
 context?: unknown
 ): OrderedMap<KM, VM>;

/**
 * Returns a new OrderedMap with only the entries for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends V>(
 predicate: (value: V, key: K, iter: this) => value is F,
 context?: unknown
 ): OrderedMap<K, F>;
 filter(
 predicate: (value: V, key: K, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new OrderedMap with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends V, C>(
 predicate: (this: C, value: V, key: K, iter: this) => value is F,
 context?: C
 ): [OrderedMap<K, V>, OrderedMap<K, F>];
 partition<C>(
 predicate: (this: C, value: V, key: K, iter: this) => unknown,
 context?: C
 ): [this, this];

/**
 * @see Collection.Keyed.flip
 */
 flip(): OrderedMap<V, K>;
 }

/**
 * A Collection of unique values with `O(log32 N)` adds and has.
 *
 * When iterating a Set, the entries will be (value, value) pairs. Iteration
 * order of a Set is undefined, however is stable. Multiple iterations of the
 * same Set will iterate in the same order.
 *
 * Set values, like Map keys, may be of any type. Equality is determined using
 * `Immutable.is`, enabling Sets to uniquely include other Immutable
 * collections, custom value types, and NaN.
 */
 namespace Set {
 /**
 * True if the provided value is a Set
 */
 function isSet(maybeSet: unknown): maybeSet is Set<unknown>;

/**
 * Creates a new Set containing `values`.
 */
 function of<T>(...values: Array<T>): Set<T>;

/**
 * `Set.fromKeys()` creates a new immutable Set containing the keys from
 * this Collection or JavaScript Object.
 */
 function fromKeys<T>(iter: Collection.Keyed<T, unknown>): Set<T>;
 // tslint:disable-next-line unified-signatures
 function fromKeys<T>(iter: Collection<T, unknown>): Set<T>;
 function fromKeys(obj: { [key: string]: unknown }): Set<string>;

/**
 * `Set.intersect()` creates a new immutable Set that is the intersection of
 * a collection of other sets.
 *
 * ```js
 * const { Set } = require('immutable')
 * const intersected = Set.intersect([
 * Set([ 'a', 'b', 'c' ])
 * Set([ 'c', 'a', 't' ])
 * ])
 * // Set [ "a", "c" ]
 * ```
 */
 function intersect<T>(sets: Iterable<Iterable<T>>): Set<T>;

/**
 * `Set.union()` creates a new immutable Set that is the union of a
 * collection of other sets.
 *
 * ```js
 * const { Set } = require('immutable')
 * const unioned = Set.union([
 * Set([ 'a', 'b', 'c' ])
 * Set([ 'c', 'a', 't' ])
 * ])
 * // Set [ "a", "b", "c", "t" ]
 * ```
 */
 function union<T>(sets: Iterable<Iterable<T>>): Set<T>;
 }

/**
 * Create a new immutable Set containing the values of the provided
 * collection-like.
 *
 * Note: `Set` is a factory function and not a class, and does not use the
 * `new` keyword during construction.
 */
 function Set<T>(collection?: Iterable<T> | ArrayLike<T>): Set<T>;

interface Set<T> extends Collection.Set<T> {
 /**
 * The number of items in this Set.
 */
 readonly size: number;

// Persistent changes

/**
     * Returns a new Set which also includes this value.
     *
     * Note: `add` can be used in `withMutations`.
     */
    add(value: T): this;

/**
     * Returns a new Set which excludes this value.
     *
     * Note: `delete` can be used in `withMutations`.
     *
     * Note: `delete` **cannot** be safely used in IE8, use `remove` if
     * supporting old browsers.
     *
     * @alias remove
     */
    delete(value: T): this;
    remove(value: T): this;

/**
     * Returns a new Set containing no values.
     *
     * Note: `clear` can be used in `withMutations`.
     */
    clear(): this;

/**
 * Returns a Set including any value from `collections` that does not already
 * exist in this Set.
 *
 * Note: `union` can be used in `withMutations`.
 * @alias merge
 * @alias concat
 */
 union<C>(...collections: Array<Iterable<C>>): Set<T | C>;
 merge<C>(...collections: Array<Iterable<C>>): Set<T | C>;
 concat<C>(...collections: Array<Iterable<C>>): Set<T | C>;

/**
 * Returns a Set which has removed any values not also contained
 * within `collections`.
 *
 * Note: `intersect` can be used in `withMutations`.
 */
 intersect(...collections: Array<Iterable<T>>): this;

/**
 * Returns a Set excluding any values contained within `collections`.
 *
 * 
 * ```js
 * const { OrderedSet } = require('immutable')
 * OrderedSet([ 1, 2, 3 ]).subtract([1, 3])
 * // OrderedSet [2]
 * ```
 *
 * Note: `subtract` can be used in `withMutations`.
 */
 subtract(...collections: Array<Iterable<T>>): this;

// Transient changes

/**
     * Note: Not all methods can be used on a mutable collection or within
     * `withMutations`! Check the documentation for each method to see if it
     * mentions being safe to use in `withMutations`.
     *
     * @see `Map#withMutations`
     */
    withMutations(mutator: (mutable: this) => unknown): this;

/**
     * @see `Map#wasAltered`
     */
    wasAltered(): boolean;

/**
     * @see `Map#asImmutable`
     */
    asImmutable(): this;

// Sequence algorithms

/**
 * Returns a new Set with values passed through a
 * `mapper` function.
 *
 * Set([1,2]).map(x => 10 * x)
 * // Set [10,20]
 */
 map<M>(
 mapper: (value: T, key: T, iter: this) => M,
 context?: unknown
 ): Set<M>;

/**
 * Flat-maps the Set, returning a new Set.
 *
 * Similar to `set.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: T, iter: this) => Iterable<M>,
 context?: unknown
 ): Set<M>;

/**
 * Returns a new Set with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, key: T, iter: this) => value is F,
 context?: unknown
 ): Set<F>;
 filter(
 predicate: (value: T, key: T, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new Set with the values for which the `predicate` function
 * returns false and another for which is returns true.
 */
 partition<F extends T, C>(
 predicate: (this: C, value: T, key: T, iter: this) => value is F,
 context?: C
 ): [Set<T>, Set<F>];
 partition<C>(
 predicate: (this: C, value: T, key: T, iter: this) => unknown,
 context?: C
 ): [this, this];
 }

/**
 * A type of Set that has the additional guarantee that the iteration order of
 * values will be the order in which they were `add`ed.
 *
 * The iteration behavior of OrderedSet is the same as native ES6 Set.
 *
 * Note that `OrderedSet` are more expensive than non-ordered `Set` and may
 * consume more memory. `OrderedSet#add` is amortized O(log32 N), but not
 * stable.
 */
 namespace OrderedSet {
 /**
 * True if the provided value is an OrderedSet.
 */
 function isOrderedSet(
 maybeOrderedSet: unknown
 ): maybeOrderedSet is OrderedSet<unknown>;

/**
 * Creates a new OrderedSet containing `values`.
 */
 function of<T>(...values: Array<T>): OrderedSet<T>;

/**
 * `OrderedSet.fromKeys()` creates a new immutable OrderedSet containing
 * the keys from this Collection or JavaScript Object.
 */
 function fromKeys<T>(iter: Collection.Keyed<T, unknown>): OrderedSet<T>;
 // tslint:disable-next-line unified-signatures
 function fromKeys<T>(iter: Collection<T, unknown>): OrderedSet<T>;
 function fromKeys(obj: { [key: string]: unknown }): OrderedSet<string>;
 }

/**
 * Create a new immutable OrderedSet containing the values of the provided
 * collection-like.
 *
 * Note: `OrderedSet` is a factory function and not a class, and does not use
 * the `new` keyword during construction.
 */
 function OrderedSet<T>(
 collection?: Iterable<T> | ArrayLike<T>
 ): OrderedSet<T>;

interface OrderedSet<T> extends Set<T> {
 /**
 * The number of items in this OrderedSet.
 */
 readonly size: number;

/**
 * Returns an OrderedSet including any value from `collections` that does
 * not already exist in this OrderedSet.
 *
 * Note: `union` can be used in `withMutations`.
 * @alias merge
 * @alias concat
 */
 union<C>(...collections: Array<Iterable<C>>): OrderedSet<T | C>;
 merge<C>(...collections: Array<Iterable<C>>): OrderedSet<T | C>;
 concat<C>(...collections: Array<Iterable<C>>): OrderedSet<T | C>;

// Sequence algorithms

/**
 * Returns a new Set with values passed through a
 * `mapper` function.
 *
 * OrderedSet([ 1, 2 ]).map(x => 10 * x)
 * // OrderedSet [10, 20]
 */
 map<M>(
 mapper: (value: T, key: T, iter: this) => M,
 context?: unknown
 ): OrderedSet<M>;

/**
 * Flat-maps the OrderedSet, returning a new OrderedSet.
 *
 * Similar to `set.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: T, iter: this) => Iterable<M>,
 context?: unknown
 ): OrderedSet<M>;

/**
 * Returns a new OrderedSet with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, key: T, iter: this) => value is F,
 context?: unknown
 ): OrderedSet<F>;
 filter(
 predicate: (value: T, key: T, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new OrderedSet with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends T, C>(
 predicate: (this: C, value: T, key: T, iter: this) => value is F,
 context?: C
 ): [OrderedSet<T>, OrderedSet<F>];
 partition<C>(
 predicate: (this: C, value: T, key: T, iter: this) => unknown,
 context?: C
 ): [this, this];

/**
 * Returns an OrderedSet of the same type "zipped" with the provided
 * collections.
 *
 * Like `zipWith`, but using the default `zipper`: creating an `Array`.
 *
 * ```js
 * const a = OrderedSet([ 1, 2, 3 ])
 * const b = OrderedSet([ 4, 5, 6 ])
 * const c = a.zip(b)
 * // OrderedSet [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
 * ```
 */
 zip(other: Collection<unknown, U>): OrderedSet<[T, U]>;
 zip<U, V>(
 other1: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): OrderedSet<[T, U, V]>;
 zip(
 ...collections: Array<Collection<unknown, unknown>>
 ): OrderedSet<unknown>;

/**
 * Returns a OrderedSet of the same type "zipped" with the provided
 * collections.
 *
 * Unlike `zip`, `zipAll` continues zipping until the longest collection is
 * exhausted. Missing values from shorter collections are filled with `undefined`.
 *
 * ```js
 * const a = OrderedSet([ 1, 2 ]);
 * const b = OrderedSet([ 3, 4, 5 ]);
 * const c = a.zipAll(b); // OrderedSet [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
 * ```
 *
 * Note: Since zipAll will return a collection as large as the largest
 * input, some results may contain undefined values. TypeScript cannot
 * account for these without cases (as of v2.5).
 */
 zipAll(other: Collection<unknown, U>): OrderedSet<[T, U]>;
 zipAll<U, V>(
 other1: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): OrderedSet<[T, U, V]>;
 zipAll(
 ...collections: Array<Collection<unknown, unknown>>
 ): OrderedSet<unknown>;

/**
 * Returns an OrderedSet of the same type "zipped" with the provided
 * collections by using a custom `zipper` function.
 *
 * @see Seq.Indexed.zipWith
 */
 zipWith<U, Z>(
 zipper: (value: T, otherValue: U) => Z,
 otherCollection: Collection<unknown, U>
 ): OrderedSet<Z>;
 zipWith<U, V, Z>(
 zipper: (value: T, otherValue: U, thirdValue: V) => Z,
 otherCollection: Collection<unknown, U>,
 thirdCollection: Collection<unknown, V>
 ): OrderedSet<Z>;
 zipWith<Z>(
 zipper: (...values: Array<unknown>) => Z,
 ...collections: Array<Collection<unknown, unknown>>
 ): OrderedSet<Z>;
 }

/**
 * Stacks are indexed collections which support very efficient O(1) addition
 * and removal from the front using `unshift(v)` and `shift()`.
 *
 * For familiarity, Stack also provides `push(v)`, `pop()`, and `peek()`, but
 * be aware that they also operate on the front of the list, unlike List or
 * a JavaScript Array.
 *
 * Note: `reverse()` or any inherent reverse traversal (`reduceRight`,
 * `lastIndexOf`, etc.) is not efficient with a Stack.
 *
 * Stack is implemented with a Single-Linked List.
 */
 namespace Stack {
 /**
 * True if the provided value is a Stack
 */
 function isStack(maybeStack: unknown): maybeStack is Stack<unknown>;

/**
 * Creates a new Stack containing `values`.
 */
 function of<T>(...values: Array<T>): Stack<T>;
 }

/**
 * Create a new immutable Stack containing the values of the provided
 * collection-like.
 *
 * The iteration order of the provided collection is preserved in the
 * resulting `Stack`.
 *
 * Note: `Stack` is a factory function and not a class, and does not use the
 * `new` keyword during construction.
 */
 function Stack<T>(collection?: Iterable<T> | ArrayLike<T>): Stack<T>;

interface Stack<T> extends Collection.Indexed<T> {
 /**
 * The number of items in this Stack.
 */
 readonly size: number;

// Reading values

/**
     * Alias for `Stack.first()`.
     */
    peek(): T | undefined;

// Persistent changes

/**
 * Returns a new Stack with 0 size and no values.
 *
 * Note: `clear` can be used in `withMutations`.
 */
 clear(): Stack<T>;

/**
 * Returns a new Stack with the provided `values` prepended, shifting other
 * values ahead to higher indices.
 *
 * This is very efficient for Stack.
 *
 * Note: `unshift` can be used in `withMutations`.
 */
 unshift(...values: Array<T>): Stack<T>;

/**
 * Like `Stack#unshift`, but accepts a collection rather than varargs.
 *
 * Note: `unshiftAll` can be used in `withMutations`.
 */
 unshiftAll(iter: Iterable<T>): Stack<T>;

/**
 * Returns a new Stack with a size ones less than this Stack, excluding
 * the first item in this Stack, shifting all other values to a lower index.
 *
 * Note: this differs from `Array#shift` because it returns a new
 * Stack rather than the removed value. Use `first()` or `peek()` to get the
 * first value in this Stack.
 *
 * Note: `shift` can be used in `withMutations`.
 */
 shift(): Stack<T>;

/**
 * Alias for `Stack#unshift` and is not equivalent to `List#push`.
 */
 push(...values: Array<T>): Stack<T>;

/**
 * Alias for `Stack#unshiftAll`.
 */
 pushAll(iter: Iterable<T>): Stack<T>;

/**
 * Alias for `Stack#shift` and is not equivalent to `List#pop`.
 */
 pop(): Stack<T>;

// Transient changes

/**
     * @see `Map#wasAltered`
     */
    wasAltered(): boolean;

/**
     * @see `Map#asImmutable`
     */
    asImmutable(): this;

// Sequence algorithms

/**
 * Returns a new Stack with other collections concatenated to this one.
 */
 concat<C>(...valuesOrCollections: Array<Iterable<C> | C>): Stack<T | C>;

/**
 * Returns a new Stack with values passed through a
 * `mapper` function.
 *
 * Stack([ 1, 2 ]).map(x => 10 * x)
 * // Stack [ 10, 20 ]
 *
 * Note: `map()` always returns a new instance, even if it produced the same
 * value at every step.
 */
 map<M>(
 mapper: (value: T, key: number, iter: this) => M,
 context?: unknown
 ): Stack<M>;

/**
 * Flat-maps the Stack, returning a new Stack.
 *
 * Similar to `stack.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: number, iter: this) => Iterable<M>,
 context?: unknown
 ): Stack<M>;

/**
 * Returns a new Set with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, index: number, iter: this) => value is F,
 context?: unknown
 ): Set<F>;
 filter(
 predicate: (value: T, index: number, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a Stack "zipped" with the provided collections.
 *
 * Like `zipWith`, but using the default `zipper`: creating an `Array`.
 *
 * ```js
 * const a = Stack([ 1, 2, 3 ]);
 * const b = Stack([ 4, 5, 6 ]);
 * const c = a.zip(b); // Stack [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
 * ```
 */
 zip(other: Collection<unknown, U>): Stack<[T, U]>;
 zip<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): Stack<[T, U, V]>;
 zip(...collections: Array<Collection<unknown, unknown>>): Stack<unknown>;

/**
 * Returns a Stack "zipped" with the provided collections.
 *
 * Unlike `zip`, `zipAll` continues zipping until the longest collection is
 * exhausted. Missing values from shorter collections are filled with `undefined`.
 *
 * ```js
 * const a = Stack([ 1, 2 ]);
 * const b = Stack([ 3, 4, 5 ]);
 * const c = a.zipAll(b); // Stack [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
 * ```
 *
 * Note: Since zipAll will return a collection as large as the largest
 * input, some results may contain undefined values. TypeScript cannot
 * account for these without cases (as of v2.5).
 */
 zipAll(other: Collection<unknown, U>): Stack<[T, U]>;
 zipAll<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): Stack<[T, U, V]>;
 zipAll(...collections: Array<Collection<unknown, unknown>>): Stack<unknown>;

/**
 * Returns a Stack "zipped" with the provided collections by using a
 * custom `zipper` function.
 *
 * ```js
 * const a = Stack([ 1, 2, 3 ]);
 * const b = Stack([ 4, 5, 6 ]);
 * const c = a.zipWith((a, b) => a + b, b);
 * // Stack [ 5, 7, 9 ]
 * ```
 */
 zipWith<U, Z>(
 zipper: (value: T, otherValue: U) => Z,
 otherCollection: Collection<unknown, U>
 ): Stack<Z>;
 zipWith<U, V, Z>(
 zipper: (value: T, otherValue: U, thirdValue: V) => Z,
 otherCollection: Collection<unknown, U>,
 thirdCollection: Collection<unknown, V>
 ): Stack<Z>;
 zipWith<Z>(
 zipper: (...values: Array<unknown>) => Z,
 ...collections: Array<Collection<unknown, unknown>>
 ): Stack<Z>;
 }

/**
 * Returns a Seq.Indexed of numbers from `start` (inclusive) to `end`
 * (exclusive), by `step`, where `start` defaults to 0, `step` to 1, and `end` to
 * infinity. When `start` is equal to `end`, returns empty range.
 *
 * Note: `Range` is a factory function and not a class, and does not use the
 * `new` keyword during construction.
 *
 * ```js
 * const { Range } = require('immutable')
 * Range() // [ 0, 1, 2, 3, ... ]
 * Range(10) // [ 10, 11, 12, 13, ... ]
 * Range(10, 15) // [ 10, 11, 12, 13, 14 ]
 * Range(10, 30, 5) // [ 10, 15, 20, 25 ]
 * Range(30, 10, 5) // [ 30, 25, 20, 15 ]
 * Range(30, 30, 5) // []
 * ```
 */
 function Range(
 start?: number,
 end?: number,
 step?: number
 ): Seq.Indexed<number>;

/**
 * Returns a Seq.Indexed of `value` repeated `times` times. When `times` is
 * not defined, returns an infinite `Seq` of `value`.
 *
 * Note: `Repeat` is a factory function and not a class, and does not use the
 * `new` keyword during construction.
 *
 * ```js
 * const { Repeat } = require('immutable')
 * Repeat('foo') // [ 'foo', 'foo', 'foo', ... ]
 * Repeat('bar', 4) // [ 'bar', 'bar', 'bar', 'bar' ]
 * ```
 */
 function Repeat<T>(value: T, times?: number): Seq.Indexed<T>;

/**
 * A record is similar to a JS object, but enforces a specific set of allowed
 * string keys, and has default values.
 *
 * The `Record()` function produces new Record Factories, which when called
 * create Record instances.
 *
 * ```js
 * const { Record } = require('immutable')
 * const ABRecord = Record({ a: 1, b: 2 })
 * const myRecord = ABRecord({ b: 3 })
 * ```
 *
 * Records always have a value for the keys they define. `remove`ing a key
 * from a record simply resets it to the default value for that key.
 *
 * ```js
 * myRecord.get('a') // 1
 * myRecord.get('b') // 3
 * const myRecordWithoutB = myRecord.remove('b')
 * myRecordWithoutB.get('b') // 2
 * ```
 *
 * Values provided to the constructor not found in the Record type will
 * be ignored. For example, in this case, ABRecord is provided a key "x" even
 * though only "a" and "b" have been defined. The value for "x" will be
 * ignored for this record.
 *
 * ```js
 * const myRecord = ABRecord({ b: 3, x: 10 })
 * myRecord.get('x') // undefined
 * ```
 *
 * Because Records have a known set of string keys, property get access works
 * as expected, however property sets will throw an Error.
 *
 * Note: IE8 does not support property access. Only use `get()` when
 * supporting IE8.
 *
 * ```js
 * myRecord.b // 3
 * myRecord.b = 5 // throws Error
 * ```
 *
 * Record Types can be extended as well, allowing for custom methods on your
 * Record. This is not a common pattern in functional environments, but is in
 * many JS programs.
 *
 * However Record Types are more restricted than typical JavaScript classes.
 * They do not use a class constructor, which also means they cannot use
 * class properties (since those are technically part of a constructor).
 *
 * While Record Types can be syntactically created with the JavaScript `class`
 * form, the resulting Record function is actually a factory function, not a
 * class constructor. Even though Record Types are not classes, JavaScript
 * currently requires the use of `new` when creating new Record instances if
 * they are defined as a `class`.
 *
 * ```
 * class ABRecord extends Record({ a: 1, b: 2 }) {
 * getAB() {
 * return this.a + this.b;
 * }
 * }
 *
 * var myRecord = new ABRecord({b: 3})
 * myRecord.getAB() // 4
 * ```
 *
 *
 * **Flow Typing Records:**
 *
 * Immutable.js exports two Flow types designed to make it easier to use
 * Records with flow typed code, `RecordOf<TProps>` and `RecordFactory<TProps>`.
 *
 * When defining a new kind of Record factory function, use a flow type that
 * describes the values the record contains along with `RecordFactory<TProps>`.
 * To type instances of the Record (which the factory function returns),
 * use `RecordOf<TProps>`.
 *
 * Typically, new Record definitions will export both the Record factory
 * function as well as the Record instance type for use in other code.
 *
 * ```js
 * import type { RecordFactory, RecordOf } from 'immutable';
 *
 * // Use RecordFactory<TProps> for defining new Record factory functions.
 * type Point3DProps = { x: number, y: number, z: number };
 * const defaultValues: Point3DProps = { x: 0, y: 0, z: 0 };
 * const makePoint3D: RecordFactory<Point3DProps> = Record(defaultValues);
 * export makePoint3D;
 *
 * // Use RecordOf<T> for defining new instances of that Record.
 * export type Point3D = RecordOf<Point3DProps>;
 * const some3DPoint: Point3D = makePoint3D({ x: 10, y: 20, z: 30 });
 * ```
 *
 * **Flow Typing Record Subclasses:**
 *
 * Records can be subclassed as a means to add additional methods to Record
 * instances. This is generally discouraged in favor of a more functional API,
 * since Subclasses have some minor overhead. However the ability to create
 * a rich API on Record types can be quite valuable.
 *
 * When using Flow to type Subclasses, do not use `RecordFactory<TProps>`,
 * instead apply the props type when subclassing:
 *
 * ```js
 * type PersonProps = {name: string, age: number};
 * const defaultValues: PersonProps = {name: 'Aristotle', age: 2400};
 * const PersonRecord = Record(defaultValues);
 * class Person extends PersonRecord<PersonProps> {
 * getName(): string {
 * return this.get('name')
 * }
 *
 * setName(name: string): this {
 * return this.set('name', name);
 * }
 * }
 * ```
 *
 * **Choosing Records vs plain JavaScript objects**
 *
 * Records offer a persistently immutable alternative to plain JavaScript
 * objects, however they're not required to be used within Immutable.js
 * collections. In fact, the deep-access and deep-updating functions
 * like `getIn()` and `setIn()` work with plain JavaScript Objects as well.
 *
 * Deciding to use Records or Objects in your application should be informed
 * by the tradeoffs and relative benefits of each:
 *
 * - *Runtime immutability*: plain JS objects may be carefully treated as
 * immutable, however Record instances will *throw* if attempted to be
 * mutated directly. Records provide this additional guarantee, however at
 * some marginal runtime cost. While JS objects are mutable by nature, the
 * use of type-checking tools like [Flow](https://medium.com/@gcanti/immutability-with-flow-faa050a1aef4)
 * can help gain confidence in code written to favor immutability.
 *
 * - *Value equality*: Records use value equality when compared with `is()`
 * or `record.equals()`. That is, two Records with the same keys and values
 * are equal. Plain objects use *reference equality*. Two objects with the
 * same keys and values are not equal since they are different objects.
 * This is important to consider when using objects as keys in a `Map` or
 * values in a `Set`, which use equality when retrieving values.
 *
 * - *API methods*: Records have a full featured API, with methods like
 * `.getIn()`, and `.equals()`. These can make working with these values
 * easier, but comes at the cost of not allowing keys with those names.
 *
 * - *Default values*: Records provide default values for every key, which
 * can be useful when constructing Records with often unchanging values.
 * However default values can make using Flow and TypeScript more laborious.
 *
 * - *Serialization*: Records use a custom internal representation to
 * efficiently store and update their values. Converting to and from this
 * form isn't free. If converting Records to plain objects is common,
 * consider sticking with plain objects to begin with.
 */
 namespace Record {
 /**
 * True if `maybeRecord` is an instance of a Record.
 */
 function isRecord(maybeRecord: unknown): maybeRecord is Record<{}>;

/**
 * Records allow passing a second parameter to supply a descriptive name
 * that appears when converting a Record to a string or in any error
 * messages. A descriptive name for any record can be accessed by using this
 * method. If one was not provided, the string "Record" is returned.
 *
 * ```js
 * const { Record } = require('immutable')
 * const Person = Record({
 * name: null
 * }, 'Person')
 *
 * var me = Person({ name: 'My Name' })
 * me.toString() // "Person { "name": "My Name" }"
 * Record.getDescriptiveName(me) // "Person"
 * ```
 */
 function getDescriptiveName(record: Record<any>): string;

/**
 * A Record.Factory is created by the `Record()` function. Record instances
 * are created by passing it some of the accepted values for that Record
 * type:
 *
 * 
 * ```js
 * // makePerson is a Record Factory function
 * const makePerson = Record({ name: null, favoriteColor: 'unknown' });
 *
 * // alan is a Record instance
 * const alan = makePerson({ name: 'Alan' });
 * ```
 *
 * Note that Record Factories return `Record<TProps> & Readonly<TProps>`,
 * this allows use of both the Record instance API, and direct property
 * access on the resulting instances:
 *
 * 
 * ```js
 * // Use the Record API
 * console.log('Record API: ' + alan.get('name'))
 *
 * // Or direct property access (Readonly)
 * console.log('property access: ' + alan.name)
 * ```
 *
 * **Flow Typing Records:**
 *
 * Use the `RecordFactory<TProps>` Flow type to get high quality type checking of
 * Records:
 *
 * ```js
 * import type { RecordFactory, RecordOf } from 'immutable';
 *
 * // Use RecordFactory<TProps> for defining new Record factory functions.
 * type PersonProps = { name: ?string, favoriteColor: string };
 * const makePerson: RecordFactory<PersonProps> = Record({ name: null, favoriteColor: 'unknown' });
 *
 * // Use RecordOf<T> for defining new instances of that Record.
 * type Person = RecordOf<PersonProps>;
 * const alan: Person = makePerson({ name: 'Alan' });
 * ```
 */
 namespace Factory {}

interface Factory<TProps extends object> {
 (values?: Partial<TProps> | Iterable<[string, unknown]>): Record<TProps> &
 Readonly<TProps>;
 new (
 values?: Partial<TProps> | Iterable<[string, unknown]>
 ): Record<TProps> & Readonly<TProps>;

/**
       * The name provided to `Record(values, name)` can be accessed with
       * `displayName`.
       */
      displayName: string;
    }

function Factory<TProps extends object>(
 values?: Partial<TProps> | Iterable<[string, unknown]>
 ): Record<TProps> & Readonly<TProps>;
 }

/**
 * Unlike other types in Immutable.js, the `Record()` function creates a new
 * Record Factory, which is a function that creates Record instances.
 *
 * See above for examples of using `Record()`.
 *
 * Note: `Record` is a factory function and not a class, and does not use the
 * `new` keyword during construction.
 */
 function Record<TProps extends object>(
 defaultValues: TProps,
 name?: string
 ): Record.Factory<TProps>;

interface Record<TProps extends object> {
 // Reading values

has(key: string): key is keyof TProps & string;

/**
 * Returns the value associated with the provided key, which may be the
 * default value defined when creating the Record factory function.
 *
 * If the requested key is not defined by this Record type, then
 * notSetValue will be returned if provided. Note that this scenario would
 * produce an error when using Flow or TypeScript.
 */
 get<K extends keyof TProps>(key: K, notSetValue?: unknown): TProps[K];
 get<T>(key: string, notSetValue: T): T;

// Reading deep values

hasIn(keyPath: Iterable<unknown>): boolean;
 getIn(keyPath: Iterable<unknown>): unknown;

// Value equality

equals(other: unknown): boolean;
    hashCode(): number;

// Persistent changes

set<K extends keyof TProps>(key: K, value: TProps[K]): this;
 update<K extends keyof TProps>(
 key: K,
 updater: (value: TProps[K]) => TProps[K]
 ): this;
 merge(
 ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
 ): this;
 mergeDeep(
 ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
 ): this;

mergeWith(
 merger: (oldVal: unknown, newVal: unknown, key: keyof TProps) => unknown,
 ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
 ): this;
 mergeDeepWith(
 merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
 ...collections: Array<Partial<TProps> | Iterable<[string, unknown]>>
 ): this;

/**
 * Returns a new instance of this Record type with the value for the
 * specific key set to its default value.
 *
 * @alias remove
 */
 delete<K extends keyof TProps>(key: K): this;
 remove<K extends keyof TProps>(key: K): this;

/**
     * Returns a new instance of this Record type with all values set
     * to their default values.
     */
    clear(): this;

// Deep persistent changes

setIn(keyPath: Iterable<unknown>, value: unknown): this;
 updateIn(
 keyPath: Iterable<unknown>,
 updater: (value: unknown) => unknown
 ): this;
 mergeIn(keyPath: Iterable<unknown>, ...collections: Array<unknown>): this;
 mergeDeepIn(
 keyPath: Iterable<unknown>,
 ...collections: Array<unknown>
 ): this;

/**
 * @alias removeIn
 */
 deleteIn(keyPath: Iterable<unknown>): this;
 removeIn(keyPath: Iterable<unknown>): this;

// Conversion to JavaScript types

/**
 * Deeply converts this Record to equivalent native JavaScript Object.
 *
 * Note: This method may not be overridden. Objects with custom
 * serialization to plain JS may override toJSON() instead.
 */
 toJS(): DeepCopy<TProps>;

/**
     * Shallowly converts this Record to equivalent native JavaScript Object.
     */
    toJSON(): TProps;

/**
     * Shallowly converts this Record to equivalent JavaScript Object.
     */
    toObject(): TProps;

// Transient changes

/**
     * Note: Not all methods can be used on a mutable collection or within
     * `withMutations`! Only `set` may be used mutatively.
     *
     * @see `Map#withMutations`
     */
    withMutations(mutator: (mutable: this) => unknown): this;

/**
     * @see `Map#asMutable`
     */
    asMutable(): this;

/**
     * @see `Map#wasAltered`
     */
    wasAltered(): boolean;

/**
     * @see `Map#asImmutable`
     */
    asImmutable(): this;

// Sequence algorithms

toSeq(): Seq.Keyed<keyof TProps, TProps[keyof TProps]>;

[Symbol.iterator](): IterableIterator<[keyof TProps, TProps[keyof TProps]]>;
 }

/**
 * RecordOf<T> is used in TypeScript to define interfaces expecting an
 * instance of record with type T.
 *
 * This is equivalent to an instance of a record created by a Record Factory.
 */
 type RecordOf<TProps extends object> = Record<TProps> & Readonly<TProps>;

/**
 * `Seq` describes a lazy operation, allowing them to efficiently chain
 * use of all the higher-order collection methods (such as `map` and `filter`)
 * by not creating intermediate collections.
 *
 * **Seq is immutable** — Once a Seq is created, it cannot be
 * changed, appended to, rearranged or otherwise modified. Instead, any
 * mutative method called on a `Seq` will return a new `Seq`.
 *
 * **Seq is lazy** — `Seq` does as little work as necessary to respond to any
 * method call. Values are often created during iteration, including implicit
 * iteration when reducing or converting to a concrete data structure such as
 * a `List` or JavaScript `Array`.
 *
 * For example, the following performs no work, because the resulting
 * `Seq`'s values are never iterated:
 *
 * ```js
 * const { Seq } = require('immutable')
 * const oddSquares = Seq([ 1, 2, 3, 4, 5, 6, 7, 8 ])
 * .filter(x => x % 2 !== 0)
 * .map(x => x * x)
 * ```
 *
 * Once the `Seq` is used, it performs only the work necessary. In this
 * example, no intermediate arrays are ever created, filter is called three
 * times, and map is only called once:
 *
 * ```js
 * oddSquares.get(1); // 9
 * ```
 *
 * Any collection can be converted to a lazy Seq with `Seq()`.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const map = Map({ a: 1, b: 2, c: 3 })
 * const lazySeq = Seq(map)
 * ```
 *
 * `Seq` allows for the efficient chaining of operations, allowing for the
 * expression of logic that can otherwise be very tedious:
 *
 * ```js
 * lazySeq
 * .flip()
 * .map(key => key.toUpperCase())
 * .flip()
 * // Seq { A: 1, B: 1, C: 1 }
 * ```
 *
 * As well as expressing logic that would otherwise seem memory or time
 * limited, for example `Range` is a special kind of Lazy sequence.
 *
 * 
 * ```js
 * const { Range } = require('immutable')
 * Range(1, Infinity)
 * .skip(1000)
 * .map(n => -n)
 * .filter(n => n % 2 === 0)
 * .take(2)
 * .reduce((r, n) => r * n, 1)
 * // 1006008
 * ```
 *
 * Seq is often used to provide a rich collection API to JavaScript Object.
 *
 * ```js
 * Seq({ x: 0, y: 1, z: 2 }).map(v => v * 2).toObject();
 * // { x: 0, y: 2, z: 4 }
 * ```
 */

namespace Seq {
 /**
 * True if `maybeSeq` is a Seq, it is not backed by a concrete
 * structure such as Map, List, or Set.
 */
 function isSeq(
 maybeSeq: unknown
 ): maybeSeq is
 | Seq.Indexed<unknown>
 | Seq.Keyed<unknown, unknown>
 | Seq.Set<unknown>;

/**
     * `Seq` which represents key-value pairs.
     */
    namespace Keyed {}

/**
 * Always returns a Seq.Keyed, if input is not keyed, expects an
 * collection of [K, V] tuples.
 *
 * Note: `Seq.Keyed` is a conversion function and not a class, and does not
 * use the `new` keyword during construction.
 */
 function Keyed<K, V>(collection?: Iterable<[K, V]>): Seq.Keyed<K, V>;
 function Keyed<V>(obj: { [key: string]: V }): Seq.Keyed<string, V>;

interface Keyed<K, V> extends Seq<K, V>, Collection.Keyed<K, V> {
 /**
 * Deeply converts this Keyed Seq to equivalent native JavaScript Object.
 *
 * Converts keys to Strings.
 */
 toJS(): { [key in string | number | symbol]: DeepCopy<V> };

/**
       * Shallowly converts this Keyed Seq to equivalent native JavaScript Object.
       *
       * Converts keys to Strings.
       */
      toJSON(): { [key in string | number | symbol]: V };

/**
 * Shallowly converts this collection to an Array.
 */
 toArray(): Array<[K, V]>;

/**
       * Returns itself
       */
      toSeq(): this;

/**
 * Returns a new Seq with other collections concatenated to this one.
 *
 * All entries will be present in the resulting Seq, even if they
 * have the same key.
 */
 concat<KC, VC>(
 ...collections: Array<Iterable<[KC, VC]>>
 ): Seq.Keyed<K | KC, V | VC>;
 concat<C>(
 ...collections: Array<{ [key: string]: C }>
 ): Seq.Keyed<K | string, V | C>;

/**
 * Returns a new Seq.Keyed with values passed through a
 * `mapper` function.
 *
 * ```js
 * const { Seq } = require('immutable')
 * Seq.Keyed({ a: 1, b: 2 }).map(x => 10 * x)
 * // Seq { "a": 10, "b": 20 }
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the
 * same value at every step.
 */
 map<M>(
 mapper: (value: V, key: K, iter: this) => M,
 context?: unknown
 ): Seq.Keyed<K, M>;

/**
 * @see Collection.Keyed.mapKeys
 */
 mapKeys<M>(
 mapper: (key: K, value: V, iter: this) => M,
 context?: unknown
 ): Seq.Keyed<M, V>;

/**
 * @see Collection.Keyed.mapEntries
 */
 mapEntries<KM, VM>(
 mapper: (
 entry: [K, V],
 index: number,
 iter: this
 ) => [KM, VM] | undefined,
 context?: unknown
 ): Seq.Keyed<KM, VM>;

/**
 * Flat-maps the Seq, returning a Seq of the same type.
 *
 * Similar to `seq.map(...).flatten(true)`.
 */
 flatMap<KM, VM>(
 mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
 context?: unknown
 ): Seq.Keyed<KM, VM>;

/**
 * Returns a new Seq with only the entries for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends V>(
 predicate: (value: V, key: K, iter: this) => value is F,
 context?: unknown
 ): Seq.Keyed<K, F>;
 filter(
 predicate: (value: V, key: K, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new keyed Seq with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends V, C>(
 predicate: (this: C, value: V, key: K, iter: this) => value is F,
 context?: C
 ): [Seq.Keyed<K, V>, Seq.Keyed<K, F>];
 partition<C>(
 predicate: (this: C, value: V, key: K, iter: this) => unknown,
 context?: C
 ): [this, this];

/**
 * @see Collection.Keyed.flip
 */
 flip(): Seq.Keyed<V, K>;

[Symbol.iterator](): IterableIterator<[K, V]>;
 }

/**
 * `Seq` which represents an ordered indexed list of values.
 */
 namespace Indexed {
 /**
 * Provides an Seq.Indexed of the values provided.
 */
 function of<T>(...values: Array<T>): Seq.Indexed<T>;
 }

/**
 * Always returns Seq.Indexed, discarding associated keys and
 * supplying incrementing indices.
 *
 * Note: `Seq.Indexed` is a conversion function and not a class, and does
 * not use the `new` keyword during construction.
 */
 function Indexed<T>(
 collection?: Iterable<T> | ArrayLike<T>
 ): Seq.Indexed<T>;

interface Indexed<T> extends Seq<number, T>, Collection.Indexed<T> {
 /**
 * Deeply converts this Indexed Seq to equivalent native JavaScript Array.
 */
 toJS(): Array<DeepCopy<T>>;

/**
 * Shallowly converts this Indexed Seq to equivalent native JavaScript Array.
 */
 toJSON(): Array<T>;

/**
 * Shallowly converts this collection to an Array.
 */
 toArray(): Array<T>;

/**
       * Returns itself
       */
      toSeq(): this;

/**
 * Returns a new Seq with other collections concatenated to this one.
 */
 concat<C>(
 ...valuesOrCollections: Array<Iterable<C> | C>
 ): Seq.Indexed<T | C>;

/**
 * Returns a new Seq.Indexed with values passed through a
 * `mapper` function.
 *
 * ```js
 * const { Seq } = require('immutable')
 * Seq.Indexed([ 1, 2 ]).map(x => 10 * x)
 * // Seq [ 10, 20 ]
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the
 * same value at every step.
 */
 map<M>(
 mapper: (value: T, key: number, iter: this) => M,
 context?: unknown
 ): Seq.Indexed<M>;

/**
 * Flat-maps the Seq, returning a a Seq of the same type.
 *
 * Similar to `seq.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: number, iter: this) => Iterable<M>,
 context?: unknown
 ): Seq.Indexed<M>;

/**
 * Returns a new Seq with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, index: number, iter: this) => value is F,
 context?: unknown
 ): Seq.Indexed<F>;
 filter(
 predicate: (value: T, index: number, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new indexed Seq with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends T, C>(
 predicate: (this: C, value: T, index: number, iter: this) => value is F,
 context?: C
 ): [Seq.Indexed<T>, Seq.Indexed<F>];
 partition<C>(
 predicate: (this: C, value: T, index: number, iter: this) => unknown,
 context?: C
 ): [this, this];

/**
 * Returns a Seq "zipped" with the provided collections.
 *
 * Like `zipWith`, but using the default `zipper`: creating an `Array`.
 *
 * ```js
 * const a = Seq([ 1, 2, 3 ]);
 * const b = Seq([ 4, 5, 6 ]);
 * const c = a.zip(b); // Seq [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
 * ```
 */
 zip(other: Collection<unknown, U>): Seq.Indexed<[T, U]>;
 zip<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): Seq.Indexed<[T, U, V]>;
 zip(
 ...collections: Array<Collection<unknown, unknown>>
 ): Seq.Indexed<unknown>;

/**
 * Returns a Seq "zipped" with the provided collections.
 *
 * Unlike `zip`, `zipAll` continues zipping until the longest collection is
 * exhausted. Missing values from shorter collections are filled with `undefined`.
 *
 * ```js
 * const a = Seq([ 1, 2 ]);
 * const b = Seq([ 3, 4, 5 ]);
 * const c = a.zipAll(b); // Seq [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
 * ```
 */
 zipAll(other: Collection<unknown, U>): Seq.Indexed<[T, U]>;
 zipAll<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): Seq.Indexed<[T, U, V]>;
 zipAll(
 ...collections: Array<Collection<unknown, unknown>>
 ): Seq.Indexed<unknown>;

/**
 * Returns a Seq "zipped" with the provided collections by using a
 * custom `zipper` function.
 *
 * ```js
 * const a = Seq([ 1, 2, 3 ]);
 * const b = Seq([ 4, 5, 6 ]);
 * const c = a.zipWith((a, b) => a + b, b);
 * // Seq [ 5, 7, 9 ]
 * ```
 */
 zipWith<U, Z>(
 zipper: (value: T, otherValue: U) => Z,
 otherCollection: Collection<unknown, U>
 ): Seq.Indexed<Z>;
 zipWith<U, V, Z>(
 zipper: (value: T, otherValue: U, thirdValue: V) => Z,
 otherCollection: Collection<unknown, U>,
 thirdCollection: Collection<unknown, V>
 ): Seq.Indexed<Z>;
 zipWith<Z>(
 zipper: (...values: Array<unknown>) => Z,
 ...collections: Array<Collection<unknown, unknown>>
 ): Seq.Indexed<Z>;

[Symbol.iterator](): IterableIterator<T>;
 }

/**
 * `Seq` which represents a set of values.
 *
 * Because `Seq` are often lazy, `Seq.Set` does not provide the same guarantee
 * of value uniqueness as the concrete `Set`.
 */
 namespace Set {
 /**
 * Returns a Seq.Set of the provided values
 */
 function of<T>(...values: Array<T>): Seq.Set<T>;
 }

/**
 * Always returns a Seq.Set, discarding associated indices or keys.
 *
 * Note: `Seq.Set` is a conversion function and not a class, and does not
 * use the `new` keyword during construction.
 */
 function Set<T>(collection?: Iterable<T> | ArrayLike<T>): Seq.Set<T>;

interface Set<T> extends Seq<T, T>, Collection.Set<T> {
 /**
 * Deeply converts this Set Seq to equivalent native JavaScript Array.
 */
 toJS(): Array<DeepCopy<T>>;

/**
 * Shallowly converts this Set Seq to equivalent native JavaScript Array.
 */
 toJSON(): Array<T>;

/**
 * Shallowly converts this collection to an Array.
 */
 toArray(): Array<T>;

/**
       * Returns itself
       */
      toSeq(): this;

/**
 * Returns a new Seq with other collections concatenated to this one.
 *
 * All entries will be present in the resulting Seq, even if they
 * are duplicates.
 */
 concat(...collections: Array<Iterable>): Seq.Set<T | U>;

/**
 * Returns a new Seq.Set with values passed through a
 * `mapper` function.
 *
 * ```js
 * Seq.Set([ 1, 2 ]).map(x => 10 * x)
 * // Seq { 10, 20 }
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the
 * same value at every step.
 */
 map<M>(
 mapper: (value: T, key: T, iter: this) => M,
 context?: unknown
 ): Seq.Set<M>;

/**
 * Flat-maps the Seq, returning a Seq of the same type.
 *
 * Similar to `seq.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: T, iter: this) => Iterable<M>,
 context?: unknown
 ): Seq.Set<M>;

/**
 * Returns a new Seq with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, key: T, iter: this) => value is F,
 context?: unknown
 ): Seq.Set<F>;
 filter(
 predicate: (value: T, key: T, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new set Seq with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends T, C>(
 predicate: (this: C, value: T, key: T, iter: this) => value is F,
 context?: C
 ): [Seq.Set<T>, Seq.Set<F>];
 partition<C>(
 predicate: (this: C, value: T, key: T, iter: this) => unknown,
 context?: C
 ): [this, this];

[Symbol.iterator](): IterableIterator<T>;
 }
 }

/**
 * Creates a Seq.
 *
 * Returns a particular kind of `Seq` based on the input.
 *
 * * If a `Seq`, that same `Seq`.
 * * If an `Collection`, a `Seq` of the same kind (Keyed, Indexed, or Set).
 * * If an Array-like, an `Seq.Indexed`.
 * * If an Iterable Object, an `Seq.Indexed`.
 * * If an Object, a `Seq.Keyed`.
 *
 * Note: An Iterator itself will be treated as an object, becoming a `Seq.Keyed`,
 * which is usually not what you want. You should turn your Iterator Object into
 * an iterable object by defining a Symbol.iterator (or @@iterator) method which
 * returns `this`.
 *
 * Note: `Seq` is a conversion function and not a class, and does not use the
 * `new` keyword during construction.
 */
 function Seq<S extends Seq<unknown, unknown>>(seq: S): S;
 function Seq<K, V>(collection: Collection.Keyed<K, V>): Seq.Keyed<K, V>;
 function Seq<T>(collection: Collection.Set<T>): Seq.Set<T>;
 function Seq<T>(
 collection: Collection.Indexed<T> | Iterable<T> | ArrayLike<T>
 ): Seq.Indexed<T>;
 function Seq<V>(obj: { [key: string]: V }): Seq.Keyed<string, V>;
 function Seq<K = unknown, V = unknown>(): Seq<K, V>;

interface Seq<K, V> extends Collection<K, V> {
 /**
 * Some Seqs can describe their size lazily. When this is the case,
 * size will be an integer. Otherwise it will be undefined.
 *
 * For example, Seqs returned from `map()` or `reverse()`
 * preserve the size of the original `Seq` while `filter()` does not.
 *
 * Note: `Range`, `Repeat` and `Seq`s made from `Array`s and `Object`s will
 * always have a size.
 */
 readonly size: number | undefined;

// Force evaluation

/**
     * Because Sequences are lazy and designed to be chained together, they do
     * not cache their results. For example, this map function is called a total
     * of 6 times, as each `join` iterates the Seq of three values.
     *
     *     var squares = Seq([ 1, 2, 3 ]).map(x => x * x)
     *     squares.join() + squares.join()
     *
     * If you know a `Seq` will be used multiple times, it may be more
     * efficient to first cache it in memory. Here, the map function is called
     * only 3 times.
     *
     *     var squares = Seq([ 1, 2, 3 ]).map(x => x * x).cacheResult()
     *     squares.join() + squares.join()
     *
     * Use this method judiciously, as it must fully evaluate a Seq which can be
     * a burden on memory and possibly performance.
     *
     * Note: after calling `cacheResult`, a Seq will always have a `size`.
     */
    cacheResult(): this;

// Sequence algorithms

/**
 * Returns a new Seq with values passed through a
 * `mapper` function.
 *
 * ```js
 * const { Seq } = require('immutable')
 * Seq([ 1, 2 ]).map(x => 10 * x)
 * // Seq [ 10, 20 ]
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the same
 * value at every step.
 */
 map<M>(
 mapper: (value: V, key: K, iter: this) => M,
 context?: unknown
 ): Seq<K, M>;

/**
 * Returns a new Seq with values passed through a
 * `mapper` function.
 *
 * ```js
 * const { Seq } = require('immutable')
 * Seq([ 1, 2 ]).map(x => 10 * x)
 * // Seq [ 10, 20 ]
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the same
 * value at every step.
 * Note: used only for sets.
 */
 map<M>(
 mapper: (value: V, key: K, iter: this) => M,
 context?: unknown
 ): Seq<M, M>;

/**
 * Flat-maps the Seq, returning a Seq of the same type.
 *
 * Similar to `seq.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: V, key: K, iter: this) => Iterable<M>,
 context?: unknown
 ): Seq<K, M>;

/**
 * Flat-maps the Seq, returning a Seq of the same type.
 *
 * Similar to `seq.map(...).flatten(true)`.
 * Note: Used only for sets.
 */
 flatMap<M>(
 mapper: (value: V, key: K, iter: this) => Iterable<M>,
 context?: unknown
 ): Seq<M, M>;

/**
 * Returns a new Seq with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends V>(
 predicate: (value: V, key: K, iter: this) => value is F,
 context?: unknown
 ): Seq<K, F>;
 filter(
 predicate: (value: V, key: K, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new Seq with the values for which the `predicate` function
 * returns false and another for which is returns true.
 */
 partition<F extends V, C>(
 predicate: (this: C, value: V, key: K, iter: this) => value is F,
 context?: C
 ): [Seq<K, V>, Seq<K, F>];
 partition<C>(
 predicate: (this: C, value: V, key: K, iter: this) => unknown,
 context?: C
 ): [this, this];
 }

/**
 * The `Collection` is a set of (key, value) entries which can be iterated, and
 * is the base class for all collections in `immutable`, allowing them to
 * make use of all the Collection methods (such as `map` and `filter`).
 *
 * Note: A collection is always iterated in the same order, however that order
 * may not always be well defined, as is the case for the `Map` and `Set`.
 *
 * Collection is the abstract base class for concrete data structures. It
 * cannot be constructed directly.
 *
 * Implementations should extend one of the subclasses, `Collection.Keyed`,
 * `Collection.Indexed`, or `Collection.Set`.
 */
 namespace Collection {
 /**
 * @deprecated use `const { isKeyed } = require('immutable')`
 */
 function isKeyed(
 maybeKeyed: unknown
 ): maybeKeyed is Collection.Keyed<unknown, unknown>;

/**
 * @deprecated use `const { isIndexed } = require('immutable')`
 */
 function isIndexed(
 maybeIndexed: unknown
 ): maybeIndexed is Collection.Indexed<unknown>;

/**
 * @deprecated use `const { isAssociative } = require('immutable')`
 */
 function isAssociative(
 maybeAssociative: unknown
 ): maybeAssociative is
 | Collection.Keyed<unknown, unknown>
 | Collection.Indexed<unknown>;

/**
     * @deprecated use `const { isOrdered } = require('immutable')`
     */
    function isOrdered(maybeOrdered: unknown): boolean;

/**
     * Keyed Collections have discrete keys tied to each value.
     *
     * When iterating `Collection.Keyed`, each iteration will yield a `[K, V]`
     * tuple, in other words, `Collection#entries` is the default iterator for
     * Keyed Collections.
     */
    namespace Keyed {}

/**
 * Creates a Collection.Keyed
 *
 * Similar to `Collection()`, however it expects collection-likes of [K, V]
 * tuples if not constructed from a Collection.Keyed or JS Object.
 *
 * Note: `Collection.Keyed` is a conversion function and not a class, and
 * does not use the `new` keyword during construction.
 */
 function Keyed<K, V>(collection?: Iterable<[K, V]>): Collection.Keyed<K, V>;
 function Keyed<V>(obj: { [key: string]: V }): Collection.Keyed<string, V>;

interface Keyed<K, V> extends Collection<K, V> {
 /**
 * Deeply converts this Keyed collection to equivalent native JavaScript Object.
 *
 * Converts keys to Strings.
 */
 toJS(): { [key in string | number | symbol]: DeepCopy<V> };

/**
       * Shallowly converts this Keyed collection to equivalent native JavaScript Object.
       *
       * Converts keys to Strings.
       */
      toJSON(): { [key in string | number | symbol]: V };

/**
 * Shallowly converts this collection to an Array.
 */
 toArray(): Array<[K, V]>;

/**
 * Returns Seq.Keyed.
 * @override
 */
 toSeq(): Seq.Keyed<K, V>;

// Sequence functions

/**
 * Returns a new Collection.Keyed of the same type where the keys and values
 * have been flipped.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ a: 'z', b: 'y' }).flip()
 * // Map { "z": "a", "y": "b" }
 * ```
 */
 flip(): Collection.Keyed<V, K>;

/**
 * Returns a new Collection with other collections concatenated to this one.
 */
 concat<KC, VC>(
 ...collections: Array<Iterable<[KC, VC]>>
 ): Collection.Keyed<K | KC, V | VC>;
 concat<C>(
 ...collections: Array<{ [key: string]: C }>
 ): Collection.Keyed<K | string, V | C>;

/**
 * Returns a new Collection.Keyed with values passed through a
 * `mapper` function.
 *
 * ```js
 * const { Collection } = require('immutable')
 * Collection.Keyed({ a: 1, b: 2 }).map(x => 10 * x)
 * // Seq { "a": 10, "b": 20 }
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the
 * same value at every step.
 */
 map<M>(
 mapper: (value: V, key: K, iter: this) => M,
 context?: unknown
 ): Collection.Keyed<K, M>;

/**
 * Returns a new Collection.Keyed of the same type with keys passed through
 * a `mapper` function.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ a: 1, b: 2 }).mapKeys(x => x.toUpperCase())
 * // Map { "A": 1, "B": 2 }
 * ```
 *
 * Note: `mapKeys()` always returns a new instance, even if it produced
 * the same key at every step.
 */
 mapKeys<M>(
 mapper: (key: K, value: V, iter: this) => M,
 context?: unknown
 ): Collection.Keyed<M, V>;

/**
 * Returns a new Collection.Keyed of the same type with entries
 * ([key, value] tuples) passed through a `mapper` function.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ a: 1, b: 2 })
 * .mapEntries(([ k, v ]) => [ k.toUpperCase(), v * 2 ])
 * // Map { "A": 2, "B": 4 }
 * ```
 *
 * Note: `mapEntries()` always returns a new instance, even if it produced
 * the same entry at every step.
 *
 * If the mapper function returns `undefined`, then the entry will be filtered
 */
 mapEntries<KM, VM>(
 mapper: (
 entry: [K, V],
 index: number,
 iter: this
 ) => [KM, VM] | undefined,
 context?: unknown
 ): Collection.Keyed<KM, VM>;

/**
 * Flat-maps the Collection, returning a Collection of the same type.
 *
 * Similar to `collection.map(...).flatten(true)`.
 */
 flatMap<KM, VM>(
 mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
 context?: unknown
 ): Collection.Keyed<KM, VM>;

/**
 * Returns a new Collection with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends V>(
 predicate: (value: V, key: K, iter: this) => value is F,
 context?: unknown
 ): Collection.Keyed<K, F>;
 filter(
 predicate: (value: V, key: K, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new keyed Collection with the values for which the
 * `predicate` function returns false and another for which is returns
 * true.
 */
 partition<F extends V, C>(
 predicate: (this: C, value: V, key: K, iter: this) => value is F,
 context?: C
 ): [Collection.Keyed<K, V>, Collection.Keyed<K, F>];
 partition<C>(
 predicate: (this: C, value: V, key: K, iter: this) => unknown,
 context?: C
 ): [this, this];

[Symbol.iterator](): IterableIterator<[K, V]>;
 }

/**
     * Indexed Collections have incrementing numeric keys. They exhibit
     * slightly different behavior than `Collection.Keyed` for some methods in order
     * to better mirror the behavior of JavaScript's `Array`, and add methods
     * which do not make sense on non-indexed Collections such as `indexOf`.
     *
     * Unlike JavaScript arrays, `Collection.Indexed`s are always dense. "Unset"
     * indices and `undefined` indices are indistinguishable, and all indices from
     * 0 to `size` are visited when iterated.
     *
     * All Collection.Indexed methods return re-indexed Collections. In other words,
     * indices always start at 0 and increment until size. If you wish to
     * preserve indices, using them as keys, convert to a Collection.Keyed by
     * calling `toKeyedSeq`.
     */
    namespace Indexed {}

/**
 * Creates a new Collection.Indexed.
 *
 * Note: `Collection.Indexed` is a conversion function and not a class, and
 * does not use the `new` keyword during construction.
 */
 function Indexed<T>(
 collection?: Iterable<T> | ArrayLike<T>
 ): Collection.Indexed<T>;

interface Indexed<T> extends Collection<number, T> {
 /**
 * Deeply converts this Indexed collection to equivalent native JavaScript Array.
 */
 toJS(): Array<DeepCopy<T>>;

/**
 * Shallowly converts this Indexed collection to equivalent native JavaScript Array.
 */
 toJSON(): Array<T>;

/**
 * Shallowly converts this collection to an Array.
 */
 toArray(): Array<T>;

// Reading values

/**
 * Returns the value associated with the provided index, or notSetValue if
 * the index is beyond the bounds of the Collection.
 *
 * `index` may be a negative number, which indexes back from the end of the
 * Collection. `s.get(-1)` gets the last item in the Collection.
 */
 get<NSV>(index: number, notSetValue: NSV): T | NSV;
 get(index: number): T | undefined;

// Conversion to Seq

/**
 * Returns Seq.Indexed.
 * @override
 */
 toSeq(): Seq.Indexed<T>;

/**
 * If this is a collection of [key, value] entry tuples, it will return a
 * Seq.Keyed of those entries.
 */
 fromEntrySeq(): Seq.Keyed<unknown, unknown>;

// Combination

/**
       * Returns a Collection of the same type with `separator` between each item
       * in this Collection.
       */
      interpose(separator: T): this;

/**
 * Returns a Collection of the same type with the provided `collections`
 * interleaved into this collection.
 *
 * The resulting Collection includes the first item from each, then the
 * second from each, etc.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * List([ 1, 2, 3 ]).interleave(List([ 'A', 'B', 'C' ]))
 * // List [ 1, "A", 2, "B", 3, "C" ]
 * ```
 *
 * The shortest Collection stops interleave.
 *
 * 
 * ```js
 * List([ 1, 2, 3 ]).interleave(
 * List([ 'A', 'B' ]),
 * List([ 'X', 'Y', 'Z' ])
 * )
 * // List [ 1, "A", "X", 2, "B", "Y" ]
 * ```
 *
 * Since `interleave()` re-indexes values, it produces a complete copy,
 * which has `O(N)` complexity.
 *
 * Note: `interleave` *cannot* be used in `withMutations`.
 */
 interleave(...collections: Array<Collection<unknown, T>>): this;

/**
 * Splice returns a new indexed Collection by replacing a region of this
 * Collection with new values. If values are not provided, it only skips the
 * region to be removed.
 *
 * `index` may be a negative number, which indexes back from the end of the
 * Collection. `s.splice(-2)` splices after the second to last item.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * List([ 'a', 'b', 'c', 'd' ]).splice(1, 2, 'q', 'r', 's')
 * // List [ "a", "q", "r", "s", "d" ]
 * ```
 *
 * Since `splice()` re-indexes values, it produces a complete copy, which
 * has `O(N)` complexity.
 *
 * Note: `splice` *cannot* be used in `withMutations`.
 */
 splice(index: number, removeNum: number, ...values: Array<T>): this;

/**
 * Returns a Collection of the same type "zipped" with the provided
 * collections.
 *
 * Like `zipWith`, but using the default `zipper`: creating an `Array`.
 *
 *
 * 
 * ```js
 * const a = List([ 1, 2, 3 ]);
 * const b = List([ 4, 5, 6 ]);
 * const c = a.zip(b); // List [ [ 1, 4 ], [ 2, 5 ], [ 3, 6 ] ]
 * ```
 */
 zip(other: Collection<unknown, U>): Collection.Indexed<[T, U]>;
 zip<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): Collection.Indexed<[T, U, V]>;
 zip(
 ...collections: Array<Collection<unknown, unknown>>
 ): Collection.Indexed<unknown>;

/**
 * Returns a Collection "zipped" with the provided collections.
 *
 * Unlike `zip`, `zipAll` continues zipping until the longest collection is
 * exhausted. Missing values from shorter collections are filled with `undefined`.
 *
 * ```js
 * const a = List([ 1, 2 ]);
 * const b = List([ 3, 4, 5 ]);
 * const c = a.zipAll(b); // List [ [ 1, 3 ], [ 2, 4 ], [ undefined, 5 ] ]
 * ```
 */
 zipAll(other: Collection<unknown, U>): Collection.Indexed<[T, U]>;
 zipAll<U, V>(
 other: Collection<unknown, U>,
 other2: Collection<unknown, V>
 ): Collection.Indexed<[T, U, V]>;
 zipAll(
 ...collections: Array<Collection<unknown, unknown>>
 ): Collection.Indexed<unknown>;

/**
 * Returns a Collection of the same type "zipped" with the provided
 * collections by using a custom `zipper` function.
 *
 * 
 * ```js
 * const a = List([ 1, 2, 3 ]);
 * const b = List([ 4, 5, 6 ]);
 * const c = a.zipWith((a, b) => a + b, b);
 * // List [ 5, 7, 9 ]
 * ```
 */
 zipWith<U, Z>(
 zipper: (value: T, otherValue: U) => Z,
 otherCollection: Collection<unknown, U>
 ): Collection.Indexed<Z>;
 zipWith<U, V, Z>(
 zipper: (value: T, otherValue: U, thirdValue: V) => Z,
 otherCollection: Collection<unknown, U>,
 thirdCollection: Collection<unknown, V>
 ): Collection.Indexed<Z>;
 zipWith<Z>(
 zipper: (...values: Array<unknown>) => Z,
 ...collections: Array<Collection<unknown, unknown>>
 ): Collection.Indexed<Z>;

// Search for value

/**
       * Returns the first index at which a given value can be found in the
       * Collection, or -1 if it is not present.
       */
      indexOf(searchValue: T): number;

/**
       * Returns the last index at which a given value can be found in the
       * Collection, or -1 if it is not present.
       */
      lastIndexOf(searchValue: T): number;

/**
       * Returns the first index in the Collection where a value satisfies the
       * provided predicate function. Otherwise -1 is returned.
       */
      findIndex(
        predicate: (value: T, index: number, iter: this) => boolean,
        context?: unknown
      ): number;

/**
       * Returns the last index in the Collection where a value satisfies the
       * provided predicate function. Otherwise -1 is returned.
       */
      findLastIndex(
        predicate: (value: T, index: number, iter: this) => boolean,
        context?: unknown
      ): number;

// Sequence algorithms

/**
 * Returns a new Collection with other collections concatenated to this one.
 */
 concat<C>(
 ...valuesOrCollections: Array<Iterable<C> | C>
 ): Collection.Indexed<T | C>;

/**
 * Returns a new Collection.Indexed with values passed through a
 * `mapper` function.
 *
 * ```js
 * const { Collection } = require('immutable')
 * Collection.Indexed([1,2]).map(x => 10 * x)
 * // Seq [ 1, 2 ]
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the
 * same value at every step.
 */
 map<M>(
 mapper: (value: T, key: number, iter: this) => M,
 context?: unknown
 ): Collection.Indexed<M>;

/**
 * Flat-maps the Collection, returning a Collection of the same type.
 *
 * Similar to `collection.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: number, iter: this) => Iterable<M>,
 context?: unknown
 ): Collection.Indexed<M>;

/**
 * Returns a new Collection with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, index: number, iter: this) => value is F,
 context?: unknown
 ): Collection.Indexed<F>;
 filter(
 predicate: (value: T, index: number, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new indexed Collection with the values for which the
 * `predicate` function returns false and another for which is returns
 * true.
 */
 partition<F extends T, C>(
 predicate: (this: C, value: T, index: number, iter: this) => value is F,
 context?: C
 ): [Collection.Indexed<T>, Collection.Indexed<F>];
 partition<C>(
 predicate: (this: C, value: T, index: number, iter: this) => unknown,
 context?: C
 ): [this, this];

[Symbol.iterator](): IterableIterator<T>;
 }

/**
     * Set Collections only represent values. They have no associated keys or
     * indices. Duplicate values are possible in the lazy `Seq.Set`s, however
     * the concrete `Set` Collection does not allow duplicate values.
     *
     * Collection methods on Collection.Set such as `map` and `forEach` will provide
     * the value as both the first and second arguments to the provided function.
     *
     * ```js
     * const { Collection } = require('immutable')
     * const seq = Collection.Set([ 'A', 'B', 'C' ])
     * // Seq { "A", "B", "C" }
     * seq.forEach((v, k) =>
     *  assert.equal(v, k)
     * )
     * ```
     */
    namespace Set {}

/**
 * Similar to `Collection()`, but always returns a Collection.Set.
 *
 * Note: `Collection.Set` is a factory function and not a class, and does
 * not use the `new` keyword during construction.
 */
 function Set<T>(collection?: Iterable<T> | ArrayLike<T>): Collection.Set<T>;

interface Set<T> extends Collection<T, T> {
 /**
 * Deeply converts this Set collection to equivalent native JavaScript Array.
 */
 toJS(): Array<DeepCopy<T>>;

/**
 * Shallowly converts this Set collection to equivalent native JavaScript Array.
 */
 toJSON(): Array<T>;

/**
 * Shallowly converts this collection to an Array.
 */
 toArray(): Array<T>;

/**
 * Returns Seq.Set.
 * @override
 */
 toSeq(): Seq.Set<T>;

// Sequence algorithms

/**
 * Returns a new Collection with other collections concatenated to this one.
 */
 concat(...collections: Array<Iterable>): Collection.Set<T | U>;

/**
 * Returns a new Collection.Set with values passed through a
 * `mapper` function.
 *
 * ```
 * Collection.Set([ 1, 2 ]).map(x => 10 * x)
 * // Seq { 1, 2 }
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the
 * same value at every step.
 */
 map<M>(
 mapper: (value: T, key: T, iter: this) => M,
 context?: unknown
 ): Collection.Set<M>;

/**
 * Flat-maps the Collection, returning a Collection of the same type.
 *
 * Similar to `collection.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: T, key: T, iter: this) => Iterable<M>,
 context?: unknown
 ): Collection.Set<M>;

/**
 * Returns a new Collection with only the values for which the `predicate`
 * function returns true.
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends T>(
 predicate: (value: T, key: T, iter: this) => value is F,
 context?: unknown
 ): Collection.Set<F>;
 filter(
 predicate: (value: T, key: T, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new set Collection with the values for which the
 * `predicate` function returns false and another for which is returns
 * true.
 */
 partition<F extends T, C>(
 predicate: (this: C, value: T, key: T, iter: this) => value is F,
 context?: C
 ): [Collection.Set<T>, Collection.Set<F>];
 partition<C>(
 predicate: (this: C, value: T, key: T, iter: this) => unknown,
 context?: C
 ): [this, this];

[Symbol.iterator](): IterableIterator<T>;
 }
 }

/**
 * Creates a Collection.
 *
 * The type of Collection created is based on the input.
 *
 * * If an `Collection`, that same `Collection`.
 * * If an Array-like, an `Collection.Indexed`.
 * * If an Object with an Iterator defined, an `Collection.Indexed`.
 * * If an Object, an `Collection.Keyed`.
 *
 * This methods forces the conversion of Objects and Strings to Collections.
 * If you want to ensure that a Collection of one item is returned, use
 * `Seq.of`.
 *
 * Note: An Iterator itself will be treated as an object, becoming a `Seq.Keyed`,
 * which is usually not what you want. You should turn your Iterator Object into
 * an iterable object by defining a Symbol.iterator (or @@iterator) method which
 * returns `this`.
 *
 * Note: `Collection` is a conversion function and not a class, and does not
 * use the `new` keyword during construction.
 */
 function Collection>(collection: I): I;
 function Collection<T>(
 collection: Iterable<T> | ArrayLike<T>
 ): Collection.Indexed<T>;
 function Collection<V>(obj: {
 [key: string]: V;
 }): Collection.Keyed<string, V>;
 function Collection<K = unknown, V = unknown>(): Collection<K, V>;

interface Collection<K, V> extends ValueObject {
 // Value equality

/**
     * True if this and the other Collection have value equality, as defined
     * by `Immutable.is()`.
     *
     * Note: This is equivalent to `Immutable.is(this, other)`, but provided to
     * allow for chained expressions.
     */
    equals(other: unknown): boolean;

// Reading values

/**
 * Returns the value associated with the provided key, or notSetValue if
 * the Collection does not contain this key.
 *
 * Note: it is possible a key may be associated with an `undefined` value,
 * so if `notSetValue` is not provided and this method returns `undefined`,
 * that does not guarantee the key was not found.
 */
 get<NSV>(key: K, notSetValue: NSV): V | NSV;
 get(key: K): V | undefined;

/**
     * True if a key exists within this `Collection`, using `Immutable.is`
     * to determine equality
     */
    has(key: K): boolean;

/**
     * True if a value exists within this `Collection`, using `Immutable.is`
     * to determine equality
     * @alias contains
     */
    includes(value: V): boolean;
    contains(value: V): boolean;

/**
 * In case the `Collection` is not empty returns the first element of the
 * `Collection`.
 * In case the `Collection` is empty returns the optional default
 * value if provided, if no default value is provided returns undefined.
 */
 first<NSV = undefined>(notSetValue?: NSV): V | NSV;

/**
 * In case the `Collection` is not empty returns the last element of the
 * `Collection`.
 * In case the `Collection` is empty returns the optional default
 * value if provided, if no default value is provided returns undefined.
 */
 last<NSV = undefined>(notSetValue?: NSV): V | NSV;

// Reading deep values

/**
 * Returns the value found by following a path of keys or indices through
 * nested Collections.
 *
 * 
 * ```js
 * const { Map, List } = require('immutable')
 * const deepData = Map({ x: List([ Map({ y: 123 }) ]) });
 * deepData.getIn(['x', 0, 'y']) // 123
 * ```
 *
 * Plain JavaScript Object or Arrays may be nested within an Immutable.js
 * Collection, and getIn() can access those values as well:
 *
 * 
 * ```js
 * const { Map, List } = require('immutable')
 * const deepData = Map({ x: [ { y: 123 } ] });
 * deepData.getIn(['x', 0, 'y']) // 123
 * ```
 */
 getIn(searchKeyPath: Iterable<unknown>, notSetValue?: unknown): unknown;

/**
 * True if the result of following a path of keys or indices through nested
 * Collections results in a set value.
 */
 hasIn(searchKeyPath: Iterable<unknown>): boolean;

// Persistent changes

/**
 * This can be very useful as a way to "chain" a normal function into a
 * sequence of methods. RxJS calls this "let" and lodash calls it "thru".
 *
 * For example, to sum a Seq after mapping and filtering:
 *
 * 
 * ```js
 * const { Seq } = require('immutable')
 *
 * function sum(collection) {
 * return collection.reduce((sum, x) => sum + x, 0)
 * }
 *
 * Seq([ 1, 2, 3 ])
 * .map(x => x + 1)
 * .filter(x => x % 2 === 0)
 * .update(sum)
 * // 6
 * ```
 */
 update<R>(updater: (value: this) => R): R;

// Conversion to JavaScript types

/**
 * Deeply converts this Collection to equivalent native JavaScript Array or Object.
 *
 * `Collection.Indexed`, and `Collection.Set` become `Array`, while
 * `Collection.Keyed` become `Object`, converting keys to Strings.
 */
 toJS():
 | Array<DeepCopy<V>>
 | { [key in string | number | symbol]: DeepCopy<V> };

/**
 * Shallowly converts this Collection to equivalent native JavaScript Array or Object.
 *
 * `Collection.Indexed`, and `Collection.Set` become `Array`, while
 * `Collection.Keyed` become `Object`, converting keys to Strings.
 */
 toJSON(): Array<V> | { [key in string | number | symbol]: V };

/**
 * Shallowly converts this collection to an Array.
 *
 * `Collection.Indexed`, and `Collection.Set` produce an Array of values.
 * `Collection.Keyed` produce an Array of [key, value] tuples.
 */
 toArray(): Array<V> | Array<[K, V]>;

/**
     * Shallowly converts this Collection to an Object.
     *
     * Converts keys to Strings.
     */
    toObject(): { [key: string]: V };

// Conversion to Collections

/**
 * Converts this Collection to a Map, Throws if keys are not hashable.
 *
 * Note: This is equivalent to `Map(this.toKeyedSeq())`, but provided
 * for convenience and to allow for chained expressions.
 */
 toMap(): Map<K, V>;

/**
 * Converts this Collection to a Map, maintaining the order of iteration.
 *
 * Note: This is equivalent to `OrderedMap(this.toKeyedSeq())`, but
 * provided for convenience and to allow for chained expressions.
 */
 toOrderedMap(): OrderedMap<K, V>;

/**
 * Converts this Collection to a Set, discarding keys. Throws if values
 * are not hashable.
 *
 * Note: This is equivalent to `Set(this)`, but provided to allow for
 * chained expressions.
 */
 toSet(): Set<V>;

/**
 * Converts this Collection to a Set, maintaining the order of iteration and
 * discarding keys.
 *
 * Note: This is equivalent to `OrderedSet(this.valueSeq())`, but provided
 * for convenience and to allow for chained expressions.
 */
 toOrderedSet(): OrderedSet<V>;

/**
 * Converts this Collection to a List, discarding keys.
 *
 * This is similar to `List(collection)`, but provided to allow for chained
 * expressions. However, when called on `Map` or other keyed collections,
 * `collection.toList()` discards the keys and creates a list of only the
 * values, whereas `List(collection)` creates a list of entry tuples.
 *
 * 
 * ```js
 * const { Map, List } = require('immutable')
 * var myMap = Map({ a: 'Apple', b: 'Banana' })
 * List(myMap) // List [ [ "a", "Apple" ], [ "b", "Banana" ] ]
 * myMap.toList() // List [ "Apple", "Banana" ]
 * ```
 */
 toList(): List<V>;

/**
 * Converts this Collection to a Stack, discarding keys. Throws if values
 * are not hashable.
 *
 * Note: This is equivalent to `Stack(this)`, but provided to allow for
 * chained expressions.
 */
 toStack(): Stack<V>;

// Conversion to Seq

/**
 * Converts this Collection to a Seq of the same kind (indexed,
 * keyed, or set).
 */
 toSeq(): Seq<K, V>;

/**
 * Returns a Seq.Keyed from this Collection where indices are treated as keys.
 *
 * This is useful if you want to operate on an
 * Collection.Indexed and preserve the [index, value] pairs.
 *
 * The returned Seq will have identical iteration order as
 * this Collection.
 *
 * 
 * ```js
 * const { Seq } = require('immutable')
 * const indexedSeq = Seq([ 'A', 'B', 'C' ])
 * // Seq [ "A", "B", "C" ]
 * indexedSeq.filter(v => v === 'B')
 * // Seq [ "B" ]
 * const keyedSeq = indexedSeq.toKeyedSeq()
 * // Seq { 0: "A", 1: "B", 2: "C" }
 * keyedSeq.filter(v => v === 'B')
 * // Seq { 1: "B" }
 * ```
 */
 toKeyedSeq(): Seq.Keyed<K, V>;

/**
 * Returns an Seq.Indexed of the values of this Collection, discarding keys.
 */
 toIndexedSeq(): Seq.Indexed<V>;

/**
 * Returns a Seq.Set of the values of this Collection, discarding keys.
 */
 toSetSeq(): Seq.Set<V>;

// Iterators

/**
 * An iterator of this `Collection`'s keys.
 *
 * Note: this will return an ES6 iterator which does not support
 * Immutable.js sequence algorithms. Use `keySeq` instead, if this is
 * what you want.
 */
 keys(): IterableIterator<K>;

/**
 * An iterator of this `Collection`'s values.
 *
 * Note: this will return an ES6 iterator which does not support
 * Immutable.js sequence algorithms. Use `valueSeq` instead, if this is
 * what you want.
 */
 values(): IterableIterator<V>;

/**
 * An iterator of this `Collection`'s entries as `[ key, value ]` tuples.
 *
 * Note: this will return an ES6 iterator which does not support
 * Immutable.js sequence algorithms. Use `entrySeq` instead, if this is
 * what you want.
 */
 entries(): IterableIterator<[K, V]>;

[Symbol.iterator](): IterableIterator<unknown>;

// Collections (Seq)

/**
 * Returns a new Seq.Indexed of the keys of this Collection,
 * discarding values.
 */
 keySeq(): Seq.Indexed<K>;

/**
 * Returns an Seq.Indexed of the values of this Collection, discarding keys.
 */
 valueSeq(): Seq.Indexed<V>;

/**
 * Returns a new Seq.Indexed of [key, value] tuples.
 */
 entrySeq(): Seq.Indexed<[K, V]>;

// Sequence algorithms

/**
 * Returns a new Collection of the same type with values passed through a
 * `mapper` function.
 *
 * 
 * ```js
 * const { Collection } = require('immutable')
 * Collection({ a: 1, b: 2 }).map(x => 10 * x)
 * // Seq { "a": 10, "b": 20 }
 * ```
 *
 * Note: `map()` always returns a new instance, even if it produced the same
 * value at every step.
 */
 map<M>(
 mapper: (value: V, key: K, iter: this) => M,
 context?: unknown
 ): Collection<K, M>;

/**
 * Note: used only for sets, which return Collection<M, M> but are otherwise
 * identical to normal `map()`.
 *
 * @ignore
 */
 map(...args: Array<never>): unknown;

/**
 * Returns a new Collection of the same type with only the entries for which
 * the `predicate` function returns true.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ a: 1, b: 2, c: 3, d: 4}).filter(x => x % 2 === 0)
 * // Map { "b": 2, "d": 4 }
 * ```
 *
 * Note: `filter()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filter<F extends V>(
 predicate: (value: V, key: K, iter: this) => value is F,
 context?: unknown
 ): Collection<K, F>;
 filter(
 predicate: (value: V, key: K, iter: this) => unknown,
 context?: unknown
 ): this;

/**
 * Returns a new Collection of the same type with only the entries for which
 * the `predicate` function returns false.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ a: 1, b: 2, c: 3, d: 4}).filterNot(x => x % 2 === 0)
 * // Map { "a": 1, "c": 3 }
 * ```
 *
 * Note: `filterNot()` always returns a new instance, even if it results in
 * not filtering out any values.
 */
 filterNot(
 predicate: (value: V, key: K, iter: this) => boolean,
 context?: unknown
 ): this;

/**
 * Returns a new Collection with the values for which the `predicate`
 * function returns false and another for which is returns true.
 */
 partition<F extends V, C>(
 predicate: (this: C, value: V, key: K, iter: this) => value is F,
 context?: C
 ): [Collection<K, V>, Collection<K, F>];
 partition<C>(
 predicate: (this: C, value: V, key: K, iter: this) => unknown,
 context?: C
 ): [this, this];

/**
     * Returns a new Collection of the same type in reverse order.
     */
    reverse(): this;

/**
 * Returns a new Collection of the same type which includes the same entries,
 * stably sorted by using a `comparator`.
 *
 * If a `comparator` is not provided, a default comparator uses `<` and `>`.
 *
 * `comparator(valueA, valueB)`:
 *
 * * Returns `0` if the elements should not be swapped.
 * * Returns `-1` (or any negative number) if `valueA` comes before `valueB`
 * * Returns `1` (or any positive number) if `valueA` comes after `valueB`
 * * Alternatively, can return a value of the `PairSorting` enum type
 * * Is pure, i.e. it must always return the same value for the same pair
 * of values.
 *
 * When sorting collections which have no defined order, their ordered
 * equivalents will be returned. e.g. `map.sort()` returns OrderedMap.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * Map({ "c": 3, "a": 1, "b": 2 }).sort((a, b) => {
 * if (a < b) { return -1; }
 * if (a > b) { return 1; }
 * if (a === b) { return 0; }
 * });
 * // OrderedMap { "a": 1, "b": 2, "c": 3 }
 * ```
 *
 * Note: `sort()` Always returns a new instance, even if the original was
 * already sorted.
 *
 * Note: This is always an eager operation.
 */
 sort(comparator?: Comparator<V>): this;

/**
 * Like `sort`, but also accepts a `comparatorValueMapper` which allows for
 * sorting by more sophisticated means:
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * const beattles = Map({
 * John: { name: "Lennon" },
 * Paul: { name: "McCartney" },
 * George: { name: "Harrison" },
 * Ringo: { name: "Starr" },
 * });
 * beattles.sortBy(member => member.name);
 * ```
 *
 * Note: `sortBy()` Always returns a new instance, even if the original was
 * already sorted.
 *
 * Note: This is always an eager operation.
 */
 sortBy<C>(
 comparatorValueMapper: (value: V, key: K, iter: this) => C,
 comparator?: Comparator<C>
 ): this;

/**
 * Returns a `Map` of `Collection`, grouped by the return
 * value of the `grouper` function.
 *
 * Note: This is always an eager operation.
 *
 * 
 * ```js
 * const { List, Map } = require('immutable')
 * const listOfMaps = List([
 * Map({ v: 0 }),
 * Map({ v: 1 }),
 * Map({ v: 1 }),
 * Map({ v: 0 }),
 * Map({ v: 2 })
 * ])
 * const groupsOfMaps = listOfMaps.groupBy(x => x.get('v'))
 * // Map {
 * // 0: List [ Map{ "v": 0 }, Map { "v": 0 } ],
 * // 1: List [ Map{ "v": 1 }, Map { "v": 1 } ],
 * // 2: List [ Map{ "v": 2 } ],
 * // }
 * ```
 */
 groupBy<G>(
 grouper: (value: V, key: K, iter: this) => G,
 context?: unknown
 ): Map<G, this>;

// Side effects

/**
     * The `sideEffect` is executed for every entry in the Collection.
     *
     * Unlike `Array#forEach`, if any call of `sideEffect` returns
     * `false`, the iteration will stop. Returns the number of entries iterated
     * (including the last iteration which returned false).
     */
    forEach(
      sideEffect: (value: V, key: K, iter: this) => unknown,
      context?: unknown
    ): number;

// Creating subsets

/**
     * Returns a new Collection of the same type representing a portion of this
     * Collection from start up to but not including end.
     *
     * If begin is negative, it is offset from the end of the Collection. e.g.
     * `slice(-2)` returns a Collection of the last two entries. If it is not
     * provided the new Collection will begin at the beginning of this Collection.
     *
     * If end is negative, it is offset from the end of the Collection. e.g.
     * `slice(0, -1)` returns a Collection of everything but the last entry. If
     * it is not provided, the new Collection will continue through the end of
     * this Collection.
     *
     * If the requested slice is equivalent to the current Collection, then it
     * will return itself.
     */
    slice(begin?: number, end?: number): this;

/**
     * Returns a new Collection of the same type containing all entries except
     * the first.
     */
    rest(): this;

/**
     * Returns a new Collection of the same type containing all entries except
     * the last.
     */
    butLast(): this;

/**
     * Returns a new Collection of the same type which excludes the first `amount`
     * entries from this Collection.
     */
    skip(amount: number): this;

/**
     * Returns a new Collection of the same type which excludes the last `amount`
     * entries from this Collection.
     */
    skipLast(amount: number): this;

/**
 * Returns a new Collection of the same type which includes entries starting
 * from when `predicate` first returns false.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
 * .skipWhile(x => x.match(/g/))
 * // List [ "cat", "hat", "god" ]
 * ```
 */
 skipWhile(
 predicate: (value: V, key: K, iter: this) => boolean,
 context?: unknown
 ): this;

/**
 * Returns a new Collection of the same type which includes entries starting
 * from when `predicate` first returns true.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
 * .skipUntil(x => x.match(/hat/))
 * // List [ "hat", "god" ]
 * ```
 */
 skipUntil(
 predicate: (value: V, key: K, iter: this) => boolean,
 context?: unknown
 ): this;

/**
     * Returns a new Collection of the same type which includes the first `amount`
     * entries from this Collection.
     */
    take(amount: number): this;

/**
     * Returns a new Collection of the same type which includes the last `amount`
     * entries from this Collection.
     */
    takeLast(amount: number): this;

/**
 * Returns a new Collection of the same type which includes entries from this
 * Collection as long as the `predicate` returns true.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
 * .takeWhile(x => x.match(/o/))
 * // List [ "dog", "frog" ]
 * ```
 */
 takeWhile(
 predicate: (value: V, key: K, iter: this) => boolean,
 context?: unknown
 ): this;

/**
 * Returns a new Collection of the same type which includes entries from this
 * Collection as long as the `predicate` returns false.
 *
 * 
 * ```js
 * const { List } = require('immutable')
 * List([ 'dog', 'frog', 'cat', 'hat', 'god' ])
 * .takeUntil(x => x.match(/at/))
 * // List [ "dog", "frog" ]
 * ```
 */
 takeUntil(
 predicate: (value: V, key: K, iter: this) => boolean,
 context?: unknown
 ): this;

// Combination

/**
 * Returns a new Collection of the same type with other values and
 * collection-like concatenated to this one.
 *
 * For Seqs, all entries will be present in the resulting Seq, even if they
 * have the same key.
 */
 concat(
 ...valuesOrCollections: Array<unknown>
 ): Collection<unknown, unknown>;

/**
 * Flattens nested Collections.
 *
 * Will deeply flatten the Collection by default, returning a Collection of the
 * same type, but a `depth` can be provided in the form of a number or
 * boolean (where true means to shallowly flatten one level). A depth of 0
 * (or shallow: false) will deeply flatten.
 *
 * Flattens only others Collection, not Arrays or Objects.
 *
 * Note: `flatten(true)` operates on Collection<unknown, Collection<K, V>> and
 * returns Collection<K, V>
 */
 flatten(depth?: number): Collection<unknown, unknown>;
 // tslint:disable-next-line unified-signatures
 flatten(shallow?: boolean): Collection<unknown, unknown>;

/**
 * Flat-maps the Collection, returning a Collection of the same type.
 *
 * Similar to `collection.map(...).flatten(true)`.
 */
 flatMap<M>(
 mapper: (value: V, key: K, iter: this) => Iterable<M>,
 context?: unknown
 ): Collection<K, M>;

/**
 * Flat-maps the Collection, returning a Collection of the same type.
 *
 * Similar to `collection.map(...).flatten(true)`.
 * Used for Dictionaries only.
 */
 flatMap<KM, VM>(
 mapper: (value: V, key: K, iter: this) => Iterable<[KM, VM]>,
 context?: unknown
 ): Collection<KM, VM>;

// Reducing a value

/**
 * Reduces the Collection to a value by calling the `reducer` for every entry
 * in the Collection and passing along the reduced value.
 *
 * If `initialReduction` is not provided, the first item in the
 * Collection will be used.
 *
 * @see `Array#reduce`.
 */
 reduce<R>(
 reducer: (reduction: R, value: V, key: K, iter: this) => R,
 initialReduction: R,
 context?: unknown
 ): R;
 reduce<R>(
 reducer: (reduction: V | R, value: V, key: K, iter: this) => R
 ): R;

/**
 * Reduces the Collection in reverse (from the right side).
 *
 * Note: Similar to this.reverse().reduce(), and provided for parity
 * with `Array#reduceRight`.
 */
 reduceRight<R>(
 reducer: (reduction: R, value: V, key: K, iter: this) => R,
 initialReduction: R,
 context?: unknown
 ): R;
 reduceRight<R>(
 reducer: (reduction: V | R, value: V, key: K, iter: this) => R
 ): R;

/**
     * True if `predicate` returns true for all entries in the Collection.
     */
    every(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown
    ): boolean;

/**
     * True if `predicate` returns true for any entry in the Collection.
     */
    some(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown
    ): boolean;

/**
     * Joins values together as a string, inserting a separator between each.
     * The default separator is `","`.
     */
    join(separator?: string): string;

/**
     * Returns true if this Collection includes no values.
     *
     * For some lazy `Seq`, `isEmpty` might need to iterate to determine
     * emptiness. At most one iteration will occur.
     */
    isEmpty(): boolean;

/**
     * Returns the size of this Collection.
     *
     * Regardless of if this Collection can describe its size lazily (some Seqs
     * cannot), this method will always return the correct size. E.g. it
     * evaluates a lazy `Seq` if necessary.
     *
     * If `predicate` is provided, then this returns the count of entries in the
     * Collection for which the `predicate` returns true.
     */
    count(): number;
    count(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown
    ): number;

/**
 * Returns a `Seq.Keyed` of counts, grouped by the return value of
 * the `grouper` function.
 *
 * Note: This is not a lazy operation.
 */
 countBy<G>(
 grouper: (value: V, key: K, iter: this) => G,
 context?: unknown
 ): Map<G, number>;

// Search for value

/**
     * Returns the first value for which the `predicate` returns true.
     */
    find(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown,
      notSetValue?: V
    ): V | undefined;

/**
     * Returns the last value for which the `predicate` returns true.
     *
     * Note: `predicate` will be called for each entry in reverse.
     */
    findLast(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown,
      notSetValue?: V
    ): V | undefined;

/**
     * Returns the first [key, value] entry for which the `predicate` returns true.
     */
    findEntry(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown,
      notSetValue?: V
    ): [K, V] | undefined;

/**
     * Returns the last [key, value] entry for which the `predicate`
     * returns true.
     *
     * Note: `predicate` will be called for each entry in reverse.
     */
    findLastEntry(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown,
      notSetValue?: V
    ): [K, V] | undefined;

/**
     * Returns the key for which the `predicate` returns true.
     */
    findKey(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown
    ): K | undefined;

/**
     * Returns the last key for which the `predicate` returns true.
     *
     * Note: `predicate` will be called for each entry in reverse.
     */
    findLastKey(
      predicate: (value: V, key: K, iter: this) => boolean,
      context?: unknown
    ): K | undefined;

/**
     * Returns the key associated with the search value, or undefined.
     */
    keyOf(searchValue: V): K | undefined;

/**
     * Returns the last key associated with the search value, or undefined.
     */
    lastKeyOf(searchValue: V): K | undefined;

/**
 * Returns the maximum value in this collection. If any values are
 * comparatively equivalent, the first one found will be returned.
 *
 * The `comparator` is used in the same way as `Collection#sort`. If it is not
 * provided, the default comparator is `>`.
 *
 * When two values are considered equivalent, the first encountered will be
 * returned. Otherwise, `max` will operate independent of the order of input
 * as long as the comparator is commutative. The default comparator `>` is
 * commutative *only* when types do not differ.
 *
 * If `comparator` returns 0 and either value is NaN, undefined, or null,
 * that value will be returned.
 */
 max(comparator?: Comparator<V>): V | undefined;

/**
 * Like `max`, but also accepts a `comparatorValueMapper` which allows for
 * comparing by more sophisticated means:
 *
 * 
 * ```js
 * const { List, } = require('immutable');
 * const l = List([
 * { name: 'Bob', avgHit: 1 },
 * { name: 'Max', avgHit: 3 },
 * { name: 'Lili', avgHit: 2 } ,
 * ]);
 * l.maxBy(i => i.avgHit); // will output { name: 'Max', avgHit: 3 }
 * ```
 */
 maxBy<C>(
 comparatorValueMapper: (value: V, key: K, iter: this) => C,
 comparator?: Comparator<C>
 ): V | undefined;

/**
 * Returns the minimum value in this collection. If any values are
 * comparatively equivalent, the first one found will be returned.
 *
 * The `comparator` is used in the same way as `Collection#sort`. If it is not
 * provided, the default comparator is `<`.
 *
 * When two values are considered equivalent, the first encountered will be
 * returned. Otherwise, `min` will operate independent of the order of input
 * as long as the comparator is commutative. The default comparator `<` is
 * commutative *only* when types do not differ.
 *
 * If `comparator` returns 0 and either value is NaN, undefined, or null,
 * that value will be returned.
 */
 min(comparator?: Comparator<V>): V | undefined;

/**
 * Like `min`, but also accepts a `comparatorValueMapper` which allows for
 * comparing by more sophisticated means:
 *
 * 
 * ```js
 * const { List, } = require('immutable');
 * const l = List([
 * { name: 'Bob', avgHit: 1 },
 * { name: 'Max', avgHit: 3 },
 * { name: 'Lili', avgHit: 2 } ,
 * ]);
 * l.minBy(i => i.avgHit); // will output { name: 'Bob', avgHit: 1 }
 * ```
 */
 minBy<C>(
 comparatorValueMapper: (value: V, key: K, iter: this) => C,
 comparator?: Comparator<C>
 ): V | undefined;

// Comparison

/**
 * True if `iter` includes every value in this Collection.
 */
 isSubset(iter: Iterable<V>): boolean;

/**
 * True if this Collection includes every value in `iter`.
 */
 isSuperset(iter: Iterable<V>): boolean;
 }

/**
   * The interface to fulfill to qualify as a Value Object.
   */
  interface ValueObject {
    /**
     * True if this and the other Collection have value equality, as defined
     * by `Immutable.is()`.
     *
     * Note: This is equivalent to `Immutable.is(this, other)`, but provided to
     * allow for chained expressions.
     */
    equals(other: unknown): boolean;

/**
 * Computes and returns the hashed identity for this Collection.
 *
 * The `hashCode` of a Collection is used to determine potential equality,
 * and is used when adding this to a `Set` or as a key in a `Map`, enabling
 * lookup via a different instance.
 *
 * 
 * ```js
 * const { List, Set } = require('immutable');
 * const a = List([ 1, 2, 3 ]);
 * const b = List([ 1, 2, 3 ]);
 * assert.notStrictEqual(a, b); // different instances
 * const set = Set([ a ]);
 * assert.equal(set.has(b), true);
 * ```
 *
 * Note: hashCode() MUST return a Uint32 number. The easiest way to
 * guarantee this is to return `myHash | 0` from a custom implementation.
 *
 * If two values have the same `hashCode`, they are [not guaranteed
 * to be equal][Hash Collision]. If two values have different `hashCode`s,
 * they must not be equal.
 *
 * Note: `hashCode()` is not guaranteed to always be called before
 * `equals()`. Most but not all Immutable.js collections use hash codes to
 * organize their internal data structures, while all Immutable.js
 * collections use equality during lookups.
 *
 * [Hash Collision]: https://en.wikipedia.org/wiki/Collision_(computer_science)
 */
 hashCode(): number;
 }

/**
 * Deeply converts plain JS objects and arrays to Immutable Maps and Lists.
 *
 * `fromJS` will convert Arrays and [array-like objects][2] to a List, and
 * plain objects (without a custom prototype) to a Map. [Iterable objects][3]
 * may be converted to List, Map, or Set.
 *
 * If a `reviver` is optionally provided, it will be called with every
 * collection as a Seq (beginning with the most nested collections
 * and proceeding to the top-level collection itself), along with the key
 * referring to each collection and the parent JS object provided as `this`.
 * For the top level, object, the key will be `""`. This `reviver` is expected
 * to return a new Immutable Collection, allowing for custom conversions from
 * deep JS objects. Finally, a `path` is provided which is the sequence of
 * keys to this value from the starting value.
 *
 * `reviver` acts similarly to the [same parameter in `JSON.parse`][1].
 *
 * If `reviver` is not provided, the default behavior will convert Objects
 * into Maps and Arrays into Lists like so:
 *
 * 
 * ```js
 * const { fromJS, isKeyed } = require('immutable')
 * function (key, value) {
 * return isKeyed(value) ? value.toMap() : value.toList()
 * }
 * ```
 *
 * Accordingly, this example converts native JS data to OrderedMap and List:
 *
 * 
 * ```js
 * const { fromJS, isKeyed } = require('immutable')
 * fromJS({ a: {b: [10, 20, 30]}, c: 40}, function (key, value, path) {
 * console.log(key, value, path)
 * return isKeyed(value) ? value.toOrderedMap() : value.toList()
 * })
 *
 * > "b", [ 10, 20, 30 ], [ "a", "b" ]
 * > "a", {b: [10, 20, 30]}, [ "a" ]
 * > "", {a: {b: [10, 20, 30]}, c: 40}, []
 * ```
 *
 * Keep in mind, when using JS objects to construct Immutable Maps, that
 * JavaScript Object properties are always strings, even if written in a
 * quote-less shorthand, while Immutable Maps accept keys of any type.
 *
 * 
 * ```js
 * const { Map } = require('immutable')
 * let obj = { 1: "one" };
 * Object.keys(obj); // [ "1" ]
 * assert.equal(obj["1"], obj[1]); // "one" === "one"
 *
 * let map = Map(obj);
 * assert.notEqual(map.get("1"), map.get(1)); // "one" !== undefined
 * ```
 *
 * Property access for JavaScript Objects first converts the key to a string,
 * but since Immutable Map keys can be of any type the argument to `get()` is
 * not altered.
 *
 * [1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse#Example.3A_Using_the_reviver_parameter
 * "Using the reviver parameter"
 * [2]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Indexed_collections#working_with_array-like_objects
 * "Working with array-like objects"
 * [3]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_iterable_protocol
 * "The iterable protocol"
 */
 function fromJS<JSValue>(
 jsValue: JSValue,
 reviver?: undefined
 ): FromJS<JSValue>;
 function fromJS(
 jsValue: unknown,
 reviver?: (
 key: string | number,
 sequence: Collection.Keyed<string, unknown> | Collection.Indexed<unknown>,
 path?: Array<string | number>
 ) => unknown
 ): Collection<unknown, unknown>;

type FromJS<JSValue> = JSValue extends FromJSNoTransform
 ? JSValue
 : JSValue extends Array<any>
 ? FromJSArray<JSValue>
 : JSValue extends {}
 ? FromJSObject<JSValue>
 : any;

type FromJSArray<JSValue> = JSValue extends Array<infer T>
 ? List<FromJS<T>>
 : never;

type FromJSObject<JSValue> = JSValue extends {}
 ? Map<keyof JSValue, FromJS<JSValue[keyof JSValue]>>
 : never;

/**
 * Value equality check with semantics similar to `Object.is`, but treats
 * Immutable `Collection`s as values, equal if the second `Collection` includes
 * equivalent values.
 *
 * It's used throughout Immutable when checking for equality, including `Map`
 * key equality and `Set` membership.
 *
 * 
 * ```js
 * const { Map, is } = require('immutable')
 * const map1 = Map({ a: 1, b: 1, c: 1 })
 * const map2 = Map({ a: 1, b: 1, c: 1 })
 * assert.equal(map1 !== map2, true)
 * assert.equal(Object.is(map1, map2), false)
 * assert.equal(is(map1, map2), true)
 * ```
 *
 * `is()` compares primitive types like strings and numbers, Immutable.js
 * collections like `Map` and `List`, but also any custom object which
 * implements `ValueObject` by providing `equals()` and `hashCode()` methods.
 *
 * Note: Unlike `Object.is`, `Immutable.is` assumes `0` and `-0` are the same
 * value, matching the behavior of ES6 Map key equality.
 */
 function is(first: unknown, second: unknown): boolean;

/**
   * The `hash()` function is an important part of how Immutable determines if
   * two values are equivalent and is used to determine how to store those
   * values. Provided with any value, `hash()` will return a 31-bit integer.
   *
   * When designing Objects which may be equal, it's important that when a
   * `.equals()` method returns true, that both values `.hashCode()` method
   * return the same value. `hash()` may be used to produce those values.
   *
   * For non-Immutable Objects that do not provide a `.hashCode()` functions
   * (including plain Objects, plain Arrays, Date objects, etc), a unique hash
   * value will be created for each *instance*. That is, the create hash
   * represents referential equality, and not value equality for Objects. This
   * ensures that if that Object is mutated over time that its hash code will
   * remain consistent, allowing Objects to be used as keys and values in
   * Immutable.js collections.
   *
   * Note that `hash()` attempts to balance between speed and avoiding
   * collisions, however it makes no attempt to produce secure hashes.
   *
   * *New in Version 4.0*
   */
  function hash(value: unknown): number;

/**
 * True if `maybeImmutable` is an Immutable Collection or Record.
 *
 * Note: Still returns true even if the collections is within a `withMutations()`.
 *
 * 
 * ```js
 * const { isImmutable, Map, List, Stack } = require('immutable');
 * isImmutable([]); // false
 * isImmutable({}); // false
 * isImmutable(Map()); // true
 * isImmutable(List()); // true
 * isImmutable(Stack()); // true
 * isImmutable(Map().asMutable()); // true
 * ```
 */
 function isImmutable(
 maybeImmutable: unknown
 ): maybeImmutable is Collection<unknown, unknown>;

/**
 * True if `maybeCollection` is a Collection, or any of its subclasses.
 *
 * 
 * ```js
 * const { isCollection, Map, List, Stack } = require('immutable');
 * isCollection([]); // false
 * isCollection({}); // false
 * isCollection(Map()); // true
 * isCollection(List()); // true
 * isCollection(Stack()); // true
 * ```
 */
 function isCollection(
 maybeCollection: unknown
 ): maybeCollection is Collection<unknown, unknown>;

/**
 * True if `maybeKeyed` is a Collection.Keyed, or any of its subclasses.
 *
 * 
 * ```js
 * const { isKeyed, Map, List, Stack } = require('immutable');
 * isKeyed([]); // false
 * isKeyed({}); // false
 * isKeyed(Map()); // true
 * isKeyed(List()); // false
 * isKeyed(Stack()); // false
 * ```
 */
 function isKeyed(
 maybeKeyed: unknown
 ): maybeKeyed is Collection.Keyed<unknown, unknown>;

/**
 * True if `maybeIndexed` is a Collection.Indexed, or any of its subclasses.
 *
 * 
 * ```js
 * const { isIndexed, Map, List, Stack, Set } = require('immutable');
 * isIndexed([]); // false
 * isIndexed({}); // false
 * isIndexed(Map()); // false
 * isIndexed(List()); // true
 * isIndexed(Stack()); // true
 * isIndexed(Set()); // false
 * ```
 */
 function isIndexed(
 maybeIndexed: unknown
 ): maybeIndexed is Collection.Indexed<unknown>;

/**
 * True if `maybeAssociative` is either a Keyed or Indexed Collection.
 *
 * 
 * ```js
 * const { isAssociative, Map, List, Stack, Set } = require('immutable');
 * isAssociative([]); // false
 * isAssociative({}); // false
 * isAssociative(Map()); // true
 * isAssociative(List()); // true
 * isAssociative(Stack()); // true
 * isAssociative(Set()); // false
 * ```
 */
 function isAssociative(
 maybeAssociative: unknown
 ): maybeAssociative is
 | Collection.Keyed<unknown, unknown>
 | Collection.Indexed<unknown>;

/**
 * True if `maybeOrdered` is a Collection where iteration order is well
 * defined. True for Collection.Indexed as well as OrderedMap and OrderedSet.
 *
 * 
 * ```js
 * const { isOrdered, Map, OrderedMap, List, Set } = require('immutable');
 * isOrdered([]); // false
 * isOrdered({}); // false
 * isOrdered(Map()); // false
 * isOrdered(OrderedMap()); // true
 * isOrdered(List()); // true
 * isOrdered(Set()); // false
 * ```
 */
 function isOrdered(maybeOrdered: unknown): boolean;

/**
   * True if `maybeValue` is a JavaScript Object which has *both* `equals()`
   * and `hashCode()` methods.
   *
   * Any two instances of *value objects* can be compared for value equality with
   * `Immutable.is()` and can be used as keys in a `Map` or members in a `Set`.
   */
  function isValueObject(maybeValue: unknown): maybeValue is ValueObject;

/**
 * True if `maybeSeq` is a Seq.
 */
 function isSeq(
 maybeSeq: unknown
 ): maybeSeq is
 | Seq.Indexed<unknown>
 | Seq.Keyed<unknown, unknown>
 | Seq.Set<unknown>;

/**
 * True if `maybeList` is a List.
 */
 function isList(maybeList: unknown): maybeList is List<unknown>;

/**
 * True if `maybeMap` is a Map.
 *
 * Also true for OrderedMaps.
 */
 function isMap(maybeMap: unknown): maybeMap is Map<unknown, unknown>;

/**
 * True if `maybeOrderedMap` is an OrderedMap.
 */
 function isOrderedMap(
 maybeOrderedMap: unknown
 ): maybeOrderedMap is OrderedMap<unknown, unknown>;

/**
 * True if `maybeStack` is a Stack.
 */
 function isStack(maybeStack: unknown): maybeStack is Stack<unknown>;

/**
 * True if `maybeSet` is a Set.
 *
 * Also true for OrderedSets.
 */
 function isSet(maybeSet: unknown): maybeSet is Set<unknown>;

/**
 * True if `maybeOrderedSet` is an OrderedSet.
 */
 function isOrderedSet(
 maybeOrderedSet: unknown
 ): maybeOrderedSet is OrderedSet<unknown>;

/**
 * True if `maybeRecord` is a Record.
 */
 function isRecord(maybeRecord: unknown): maybeRecord is Record<{}>;

/**
 * Returns the value within the provided collection associated with the
 * provided key, or notSetValue if the key is not defined in the collection.
 *
 * A functional alternative to `collection.get(key)` which will also work on
 * plain Objects and Arrays as an alternative for `collection[key]`.
 *
 * 
 * ```js
 * const { get } = require('immutable')
 * get([ 'dog', 'frog', 'cat' ], 2) // 'frog'
 * get({ x: 123, y: 456 }, 'x') // 123
 * get({ x: 123, y: 456 }, 'z', 'ifNotSet') // 'ifNotSet'
 * ```
 */
 function get<K, V>(collection: Collection<K, V>, key: K): V | undefined;
 function get<K, V, NSV>(
 collection: Collection<K, V>,
 key: K,
 notSetValue: NSV
 ): V | NSV;
 function get<TProps extends object, K extends keyof TProps>(
 record: Record<TProps>,
 key: K,
 notSetValue: unknown
 ): TProps[K];
 function get<V>(collection: Array<V>, key: number): V | undefined;
 function get<V, NSV>(
 collection: Array<V>,
 key: number,
 notSetValue: NSV
 ): V | NSV;
 function get<C extends object, K extends keyof C>(
 object: C,
 key: K,
 notSetValue: unknown
 ): C[K];
 function get<V>(collection: { [key: string]: V }, key: string): V | undefined;
 function get<V, NSV>(
 collection: { [key: string]: V },
 key: string,
 notSetValue: NSV
 ): V | NSV;

/**
 * Returns true if the key is defined in the provided collection.
 *
 * A functional alternative to `collection.has(key)` which will also work with
 * plain Objects and Arrays as an alternative for
 * `collection.hasOwnProperty(key)`.
 *
 * 
 * ```js
 * const { has } = require('immutable')
 * has([ 'dog', 'frog', 'cat' ], 2) // true
 * has([ 'dog', 'frog', 'cat' ], 5) // false
 * has({ x: 123, y: 456 }, 'x') // true
 * has({ x: 123, y: 456 }, 'z') // false
 * ```
 */
 function has(collection: object, key: unknown): boolean;

/**
 * Returns a copy of the collection with the value at key removed.
 *
 * A functional alternative to `collection.remove(key)` which will also work
 * with plain Objects and Arrays as an alternative for
 * `delete collectionCopy[key]`.
 *
 * 
 * ```js
 * const { remove } = require('immutable')
 * const originalArray = [ 'dog', 'frog', 'cat' ]
 * remove(originalArray, 1) // [ 'dog', 'cat' ]
 * console.log(originalArray) // [ 'dog', 'frog', 'cat' ]
 * const originalObject = { x: 123, y: 456 }
 * remove(originalObject, 'x') // { y: 456 }
 * console.log(originalObject) // { x: 123, y: 456 }
 * ```
 */
 function remove<K, C extends Collection<K, unknown>>(
 collection: C,
 key: K
 ): C;
 function remove<
 TProps extends object,
 C extends Record<TProps>,
 K extends keyof TProps
 >(collection: C, key: K): C;
 function remove<C extends Array<unknown>>(collection: C, key: number): C;
 function remove<C, K extends keyof C>(collection: C, key: K): C;
 function remove<C extends { [key: string]: unknown }, K extends keyof C>(
 collection: C,
 key: K
 ): C;

/**
 * Returns a copy of the collection with the value at key set to the provided
 * value.
 *
 * A functional alternative to `collection.set(key, value)` which will also
 * work with plain Objects and Arrays as an alternative for
 * `collectionCopy[key] = value`.
 *
 * 
 * ```js
 * const { set } = require('immutable')
 * const originalArray = [ 'dog', 'frog', 'cat' ]
 * set(originalArray, 1, 'cow') // [ 'dog', 'cow', 'cat' ]
 * console.log(originalArray) // [ 'dog', 'frog', 'cat' ]
 * const originalObject = { x: 123, y: 456 }
 * set(originalObject, 'x', 789) // { x: 789, y: 456 }
 * console.log(originalObject) // { x: 123, y: 456 }
 * ```
 */
 function set<K, V, C extends Collection<K, V>>(
 collection: C,
 key: K,
 value: V
 ): C;
 function set<
 TProps extends object,
 C extends Record<TProps>,
 K extends keyof TProps
 >(record: C, key: K, value: TProps[K]): C;
 function set<V, C extends Array<V>>(collection: C, key: number, value: V): C;
 function set<C, K extends keyof C>(object: C, key: K, value: C[K]): C;
 function set<V, C extends { [key: string]: V }>(
 collection: C,
 key: string,
 value: V
 ): C;

/**
 * Returns a copy of the collection with the value at key set to the result of
 * providing the existing value to the updating function.
 *
 * A functional alternative to `collection.update(key, fn)` which will also
 * work with plain Objects and Arrays as an alternative for
 * `collectionCopy[key] = fn(collection[key])`.
 *
 * 
 * ```js
 * const { update } = require('immutable')
 * const originalArray = [ 'dog', 'frog', 'cat' ]
 * update(originalArray, 1, val => val.toUpperCase()) // [ 'dog', 'FROG', 'cat' ]
 * console.log(originalArray) // [ 'dog', 'frog', 'cat' ]
 * const originalObject = { x: 123, y: 456 }
 * update(originalObject, 'x', val => val * 6) // { x: 738, y: 456 }
 * console.log(originalObject) // { x: 123, y: 456 }
 * ```
 */
 function update<K, V, C extends Collection<K, V>>(
 collection: C,
 key: K,
 updater: (value: V | undefined) => V | undefined
 ): C;
 function update<K, V, C extends Collection<K, V>, NSV>(
 collection: C,
 key: K,
 notSetValue: NSV,
 updater: (value: V | NSV) => V
 ): C;
 function update<
 TProps extends object,
 C extends Record<TProps>,
 K extends keyof TProps
 >(record: C, key: K, updater: (value: TProps[K]) => TProps[K]): C;
 function update<
 TProps extends object,
 C extends Record<TProps>,
 K extends keyof TProps,
 NSV
 >(
 record: C,
 key: K,
 notSetValue: NSV,
 updater: (value: TProps[K] | NSV) => TProps[K]
 ): C;
 function update<V>(
 collection: Array<V>,
 key: number,
 updater: (value: V | undefined) => V | undefined
 ): Array<V>;
 function update<V, NSV>(
 collection: Array<V>,
 key: number,
 notSetValue: NSV,
 updater: (value: V | NSV) => V
 ): Array<V>;
 function update<C, K extends keyof C>(
 object: C,
 key: K,
 updater: (value: C[K]) => C[K]
 ): C;
 function update<C, K extends keyof C, NSV>(
 object: C,
 key: K,
 notSetValue: NSV,
 updater: (value: C[K] | NSV) => C[K]
 ): C;
 function update<V, C extends { [key: string]: V }, K extends keyof C>(
 collection: C,
 key: K,
 updater: (value: V) => V
 ): { [key: string]: V };
 function update<V, C extends { [key: string]: V }, K extends keyof C, NSV>(
 collection: C,
 key: K,
 notSetValue: NSV,
 updater: (value: V | NSV) => V
 ): { [key: string]: V };

/**
 * Returns the value at the provided key path starting at the provided
 * collection, or notSetValue if the key path is not defined.
 *
 * A functional alternative to `collection.getIn(keypath)` which will also
 * work with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { getIn } = require('immutable')
 * getIn({ x: { y: { z: 123 }}}, ['x', 'y', 'z']) // 123
 * getIn({ x: { y: { z: 123 }}}, ['x', 'q', 'p'], 'ifNotSet') // 'ifNotSet'
 * ```
 */
 function getIn(
 collection: unknown,
 keyPath: Iterable<unknown>,
 notSetValue?: unknown
 ): unknown;

/**
 * Returns true if the key path is defined in the provided collection.
 *
 * A functional alternative to `collection.hasIn(keypath)` which will also
 * work with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { hasIn } = require('immutable')
 * hasIn({ x: { y: { z: 123 }}}, ['x', 'y', 'z']) // true
 * hasIn({ x: { y: { z: 123 }}}, ['x', 'q', 'p']) // false
 * ```
 */
 function hasIn(collection: unknown, keyPath: Iterable<unknown>): boolean;

/**
 * Returns a copy of the collection with the value at the key path removed.
 *
 * A functional alternative to `collection.removeIn(keypath)` which will also
 * work with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { removeIn } = require('immutable')
 * const original = { x: { y: { z: 123 }}}
 * removeIn(original, ['x', 'y', 'z']) // { x: { y: {}}}
 * console.log(original) // { x: { y: { z: 123 }}}
 * ```
 */
 function removeIn<C>(collection: C, keyPath: Iterable<unknown>): C;

/**
 * Returns a copy of the collection with the value at the key path set to the
 * provided value.
 *
 * A functional alternative to `collection.setIn(keypath)` which will also
 * work with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { setIn } = require('immutable')
 * const original = { x: { y: { z: 123 }}}
 * setIn(original, ['x', 'y', 'z'], 456) // { x: { y: { z: 456 }}}
 * console.log(original) // { x: { y: { z: 123 }}}
 * ```
 */
 function setIn<C>(
 collection: C,
 keyPath: Iterable<unknown>,
 value: unknown
 ): C;

/**
 * Returns a copy of the collection with the value at key path set to the
 * result of providing the existing value to the updating function.
 *
 * A functional alternative to `collection.updateIn(keypath)` which will also
 * work with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { updateIn } = require('immutable')
 * const original = { x: { y: { z: 123 }}}
 * updateIn(original, ['x', 'y', 'z'], val => val * 6) // { x: { y: { z: 738 }}}
 * console.log(original) // { x: { y: { z: 123 }}}
 * ```
 */
 function updateIn<C>(
 collection: C,
 keyPath: Iterable<unknown>,
 updater: (value: unknown) => unknown
 ): C;
 function updateIn<C>(
 collection: C,
 keyPath: Iterable<unknown>,
 notSetValue: unknown,
 updater: (value: unknown) => unknown
 ): C;

/**
 * Returns a copy of the collection with the remaining collections merged in.
 *
 * A functional alternative to `collection.merge()` which will also work with
 * plain Objects and Arrays.
 *
 * 
 * ```js
 * const { merge } = require('immutable')
 * const original = { x: 123, y: 456 }
 * merge(original, { y: 789, z: 'abc' }) // { x: 123, y: 789, z: 'abc' }
 * console.log(original) // { x: 123, y: 456 }
 * ```
 */
 function merge<C>(
 collection: C,
 ...collections: Array<
 | Iterable<unknown>
 | Iterable<[unknown, unknown]>
 | { [key: string]: unknown }
 >
 ): C;

/**
 * Returns a copy of the collection with the remaining collections merged in,
 * calling the `merger` function whenever an existing value is encountered.
 *
 * A functional alternative to `collection.mergeWith()` which will also work
 * with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { mergeWith } = require('immutable')
 * const original = { x: 123, y: 456 }
 * mergeWith(
 * (oldVal, newVal) => oldVal + newVal,
 * original,
 * { y: 789, z: 'abc' }
 * ) // { x: 123, y: 1245, z: 'abc' }
 * console.log(original) // { x: 123, y: 456 }
 * ```
 */
 function mergeWith<C>(
 merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
 collection: C,
 ...collections: Array<
 | Iterable<unknown>
 | Iterable<[unknown, unknown]>
 | { [key: string]: unknown }
 >
 ): C;

/**
 * Like `merge()`, but when two compatible collections are encountered with
 * the same key, it merges them as well, recursing deeply through the nested
 * data. Two collections are considered to be compatible (and thus will be
 * merged together) if they both fall into one of three categories: keyed
 * (e.g., `Map`s, `Record`s, and objects), indexed (e.g., `List`s and
 * arrays), or set-like (e.g., `Set`s). If they fall into separate
 * categories, `mergeDeep` will replace the existing collection with the
 * collection being merged in. This behavior can be customized by using
 * `mergeDeepWith()`.
 *
 * Note: Indexed and set-like collections are merged using
 * `concat()`/`union()` and therefore do not recurse.
 *
 * A functional alternative to `collection.mergeDeep()` which will also work
 * with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { mergeDeep } = require('immutable')
 * const original = { x: { y: 123 }}
 * mergeDeep(original, { x: { z: 456 }}) // { x: { y: 123, z: 456 }}
 * console.log(original) // { x: { y: 123 }}
 * ```
 */
 function mergeDeep<C>(
 collection: C,
 ...collections: Array<
 | Iterable<unknown>
 | Iterable<[unknown, unknown]>
 | { [key: string]: unknown }
 >
 ): C;

/**
 * Like `mergeDeep()`, but when two non-collections or incompatible
 * collections are encountered at the same key, it uses the `merger` function
 * to determine the resulting value. Collections are considered incompatible
 * if they fall into separate categories between keyed, indexed, and set-like.
 *
 * A functional alternative to `collection.mergeDeepWith()` which will also
 * work with plain Objects and Arrays.
 *
 * 
 * ```js
 * const { mergeDeepWith } = require('immutable')
 * const original = { x: { y: 123 }}
 * mergeDeepWith(
 * (oldVal, newVal) => oldVal + newVal,
 * original,
 * { x: { y: 456 }}
 * ) // { x: { y: 579 }}
 * console.log(original) // { x: { y: 123 }}
 * ```
 */
 function mergeDeepWith<C>(
 merger: (oldVal: unknown, newVal: unknown, key: unknown) => unknown,
 collection: C,
 ...collections: Array<
 | Iterable<unknown>
 | Iterable<[unknown, unknown]>
 | { [key: string]: unknown }
 >
 ): C;
}

/**
 * Defines the main export of the immutable module to be the Immutable namespace
 * This supports many common module import patterns:
 *
 *     const Immutable = require("immutable");
 *     const { List } = require("immutable");
 *     import Immutable from "immutable";
 *     import * as Immutable from "immutable";
 *     import { List } from "immutable";
 *
 */
export = Immutable;

/**
 * A global "Immutable" namespace used by UMD modules which allows the use of
 * the full Immutable API.
 *
 * If using Immutable as an imported module, prefer using:
 *
 *     import Immutable from 'immutable'
 *
 */
export as namespace Immutable;