docs: def _to_dict(self):
          """Return a json dictionary representing this model."""
          _dict = {}
          if hasattr(self,
                     'matching_results') and self.matching_results is not None:
              _dict['matching_results'] = self.matching_results
          if hasattr(self, 'hits') and self.hits is not None:
              _dict['hits'] = [x._to_dict() for x in self.hits]
          return _dict