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