docs: def _from_dict(cls, _dict):
          """Initialize a Source object from a json dictionary."""
          args = {}
          if 'type' in _dict:
              args['type'] = _dict.get('type')
          if 'credential_id' in _dict:
              args['credential_id'] = _dict.get('credential_id')
          if 'schedule' in _dict:
              args['schedule'] = SourceSchedule._from_dict(_dict.get('schedule'))
          if 'options' in _dict:
              args['options'] = SourceOptions._from_dict(_dict.get('options'))
          return cls(**args)