docs: function(options) {
              options = options || {};
              options.idsToFetch = options.idsToFetch || this.trackedIds;
              options.setOptions = options.setOptions || {remove: false};
              return this.__loadWrapper(function() {
                if (options.idsToFetch && options.idsToFetch.length) {
                  return parentInstance.fetchByIds(options);
                } else {
                  return $.Deferred().resolve().promise();
                }
              });
            }