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