code: function get(key) {
      if (_isObject(key)) {
        var data = getWeak(key);
        if (data === true) return uncaughtFrozenStore(_validateCollection(this, WEAK_MAP)).get(key);
        return data ? data[this._i] : undefined;
      }
    }
docs: 23.3.3.3 WeakMap.prototype.get(key)