docs: function() {
          if (this.length === 1 && this.__frozen) {
              this.__frozen = false;
              this._unfreezeCallbacks();
              this.trigger("Unfreeze", this);
          } else {
              for (var i = 0; i < this.length; i++) {
                  var e = entities[this[i]];
                  if (e && e.__frozen) {
                      e.__frozen = false;
                      e._unfreezeCallbacks();
                      e.trigger("Unfreeze", e);
                  }
              }
          }
          return this;
      }