code: func (conn *Conn) RoundTripSingleResponse(req []byte) (resp []byte, err error) {
  	if err = conn.SendMessage(req); err != nil {
  		return nil, err
  	}
  
  	if _, err = conn.ReadStatus(string(req)); err != nil {
  		return nil, err
  	}
  
  	return conn.ReadMessage()
  }
docs: // RoundTripSingleResponse sends a message to the server, and reads a single
  // message response. If the reponse has a failure status code, returns it as an error.