code: function(models, options) {
        if (_.isArray(models)) {
          for (var i = 0, l = models.length; i < l; i++) {
            this._remove(models[i], options);
          }
        } else {
          this._remove(models, options);
        }
        return this;
      }
docs: Remove a model, or a list of models from the set. Pass silent to avoid firing the `removed` event for every model removed.