code: def _operation_status(self):
      
      if not google_v2_operations.is_done(self._op):
        return 'RUNNING'
      if google_v2_operations.is_success(self._op):
        return 'SUCCESS'
      if google_v2_operations.is_canceled(self._op):
        return 'CANCELED'
      if google_v2_operations.is_failed(self._op):
        return 'FAILURE'
  
      raise ValueError('Status for operation {} could not be determined'.format(
          self._op['name']))
docs: Returns the status of this operation.
  
      Raises:
        ValueError: if the operation status cannot be determined.
  
      Returns:
        A printable status string (RUNNING, SUCCESS, CANCELED or FAILURE).