code: func (h *Handler) ProxyHostPort() string {
  	// addr equals to "localhost:8030" at this point
  	addr := h.cfg.ProxyWebAddr.String()
  	// add the SSH port number and return
  	_, sshPort, err := net.SplitHostPort(h.cfg.ProxySSHAddr.String())
  	if err != nil {
  		log.Error(err)
  		sshPort = strconv.Itoa(defaults.SSHProxyListenPort)
  	}
  	return fmt.Sprintf("%s,%s", addr, sshPort)
  }
docs: // ProxyHostPort returns the address of the proxy server using --proxy
  // notation, i.e. "localhost:8030,8023"