private _values: { [key: string]: [K, V] } = {};

  private _kvalues: { [key: string]: [K, V] } = {};

    this._values[key.hash()] = [key, value];

    this._kvalues[key.hash()] = [key, value];

    delete this._values[key.hash()];

    delete this._kvalues[key.hash()];

    return this._values[key.hash()][1];

    return this._kvalues[key.hash()][1];

    return this.get(key) !== undefined && key.hash() in this._values;

    return this.get(key) !== undefined && key.hash() in this._kvalues;

    return Object.keys(this._values).map(key => this._values[key][0]);

    return Object.keys(this._kvalues).map(key => this._kvalues[key][0]);

    return Object.keys(this._values).map(key => this._values[key]);

    return Object.keys(this._kvalues).map(key => this._kvalues[key]);

    return Object.keys(this._values).map(key => this._values[key][1]);

    return Object.keys(this._kvalues).map(key => this._kvalues[key][1]);
  }
  hashKeyset(): string {
    const hashes: number[] = Object.keys(this._kvalues).map(s => hashCode(s));
    let code: number = hashes.reduce((pv, cv) => pv + cv);
    return code.toString();