/** @private */
  var Map = root.Map || (function () {

    function Map() {
      this._keys = [];
      this._values = [];
    }

    Map.prototype.get = function (key) {
      var i = this._keys.indexOf(key);
      return i !== -1 ? this._values[i] : undefined;
    };

    Map.prototype.set = function (key, value) {
      var i = this._keys.indexOf(key);
      i !== -1 && (this._values[i] = value);
      this._values[this._keys.push(key) - 1] = value;
    };

    Map.prototype.forEach = function (callback, thisArg) {
      for (var i = 0, len = this._keys.length; i < len; i++) {
        callback.call(thisArg, this._values[i], this._keys[i]);
      }
    };

    return Map;
  }());