/**
 * Check for equality by structure of two values
 * * Returns true if strict equality (`===`) returns true
 * * Values of different `typeof` return `false`
 * * Objects with different constructors return `false`
 * * Dates return true if both `>` and `<` return false
 * * ArrayBuffers return true when byteLength are equal and if values at all indexes are equal
 * * Arrays return true when lengths are equal and when values at all indexes pass `isEqual()` recursively
 * * Sets returns true when both are empty or when all keys equal on both
 * * Maps returns true when both are empty, when all keys equal on both, and when those key's values pass `isEqual()` recursively
 * * Dispatches to first argument's prototype method `equals: (other) => boolean` if exists
 * * Objects return true when both share same enumerable keys and all key's values  pass `isEqual()` recursively
 *
 * Exceptions:
 * * Functions, Promises, WeakSets, and WeakMaps are checked by reference
 *
 * Notes:
 * * `isEqual({}, Object.create(null))` will always be `false`, regardless of keys/values because they don't share the same constructor
 *
 * @category Helpers
 * @returns boolean indicating whether the values are equal in value, structure, or reference
 */
export declare const isEqual: <T>(x: T, y: T) => boolean;