docs: def _to_dict(self):
          """Return a json dictionary representing this model."""
          _dict = {}
          if hasattr(self, 'from_') and self.from_ is not None:
              _dict['from'] = self.from_
          if hasattr(self, 'to') and self.to is not None:
              _dict['to'] = self.to
          if hasattr(self, 'speaker') and self.speaker is not None:
              _dict['speaker'] = self.speaker
          if hasattr(self, 'confidence') and self.confidence is not None:
              _dict['confidence'] = self.confidence
          if hasattr(self, 'final_results') and self.final_results is not None:
              _dict['final'] = self.final_results
          return _dict