docs: def _validate_sort_field(self, sort_by):
          """
          :param sort_by: string
          :raises: pybomb.exceptions.InvalidSortFieldException
          """
          if (
              sort_by not in self.RESPONSE_FIELD_MAP
              or not self.RESPONSE_FIELD_MAP[sort_by].is_sort
          ):
              raise InvalidSortFieldException(
                  '"{0}" is an invalid sort field'.format(sort_by)
              )