code: function(fetchOptions = {}, options) {
          var self = this;
          var request = _request(
            'classes',
            this.className,
            this.id,
            'GET',
            transformFetchOptions(fetchOptions),
            options
          );
          return request.then(function(response) {
            const fetchedAttrs = self.parse(response);
            if (!fetchOptions.keys) self._cleanupUnsetKeys(fetchedAttrs);
            self._finishFetch(fetchedAttrs, true);
            return self;
          });
        }
docs: Fetch the model from the server. If the server's representation of the
  model differs from its current attributes, they will be overriden,
  triggering a <code>"change"</code> event.
  @param {Object} fetchOptions Optional options to set 'keys',
  'include' and 'includeACL' option.
  @param {AuthOptions} options
  @return {Promise} A promise that is fulfilled when the fetch
  completes.