declare global {
  interface MapConstructor {
    new<K extends Narrowable, V>(entries: [K, V][]): AccumulativeMap<K, V>;
  }

  /**
   * A map that can only grow. It guarantees the existence of its elements.
   *
   * @alias TotalMap
   * @alias FinalMap
   * @alias AccumulativeMap
   * @alias ImmutableMap
   */
  interface AccumulativeMap<K, V> extends Map<K, V> {
    forEach(callbackfn: (value: V, key: K, map: AccumulativeMap<K, V>) => void, thisArg?: any): void;
    get(key: K): V;
    delete(this: never): never;
    clear(this: never): never;
  }
}