code: function (id, options) {
              var self = this;
              return this._checkTransaction(options, function () {
                  return self.findById(id).chain(function (model) {
                      return model ? model.remove(options) : null;
                  });
              });
          }
docs: Similar to remove but takes an id or an array for a composite key.
  
  @example
  
  User.removeById(1);
  
  @param id id or an array for a composite key, to find the model by
  @param {Object} [options] additional options.
  @param {Boolean} [options.transaction] boolean indicating if a transaction should be used when
  removing the model.
  
  @return {comb.Promise} called back when the removal completes.