code: function (model) {
          var newModels = slice.call(this.models);
          var modelIndex = newModels.indexOf(model);
          if (modelIndex > -1) {
              newModels.splice(modelIndex, 1);
              this.models = newModels;
              this._removeIndex(this._indexes, model);
              return true;
          }
          return false;
      }
docs: Remove a model if it's in this filtered collection