code: function setCurrentFilter(filter) {
      var token = cache.get('token');
      var dfrd = Q.defer();
      var id;
      if (!token) {
        dfrd.reject(MODULE_ERRORS.undefinedToken);
      } else {
        id = typeof filter === 'string' ? filter : filter.id;
        request(format(URLs.setCurrentFilter, PROTOCOL, conf.host, id,
          token), function(err, res, body) {
          if (err) {
            dfrd.reject(err);
          } else {
            _extractEmptyResponse(body, dfrd);
            dfrd.resolve(true);
          }
        });
      }
      return dfrd.promise;
    }
docs: Sets the current Filter. I'm not sure what this does exactly.
  @method setCurrentFilter
  @param {Filter|string} filter Filter object or string ID
  @see class fogbugz.Filter
  @returns {Promise.<boolean>} True if success