code: func NewServiceUnavailable(reason string) error {
  	return &StatusError{unversioned.Status{
  		Status:  unversioned.StatusFailure,
  		Code:    http.StatusServiceUnavailable,
  		Reason:  unversioned.StatusReasonServiceUnavailable,
  		Message: reason,
  	}}
  }
docs: // NewServiceUnavailable creates an error that indicates that the requested service is unavailable.