docs: def _to_dict(self):
          """Return a json dictionary representing this model."""
          _dict = {}
          if hasattr(self, 'field_name') and self.field_name is not None:
              _dict['field'] = self.field_name
          if hasattr(self, 'field_type') and self.field_type is not None:
              _dict['type'] = self.field_type
          return _dict