code: func NewNetAddressIPPort(ip net.IP, port uint16) *NetAddress {
  	na := &NetAddress{
  		IP:   ip,
  		Port: port,
  		str: net.JoinHostPort(
  			ip.String(),
  			strconv.FormatUint(uint64(port), 10),
  		),
  	}
  	return na
  }
docs: // NewNetAddressIPPort returns a new NetAddress using the provided IP
  // and port number.