code: func (s *service) String() string {
  	if s.fwm != 0 {
  		return fmt.Sprintf("%v/fwm:%d", s.ip, s.fwm)
  	}
  	ip := s.ip.String()
  	port := strconv.Itoa(int(s.port))
  	return fmt.Sprintf("%v/%v", net.JoinHostPort(ip, port), s.proto)
  }
docs: // String returns a string representing a service.