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