code: func replaceHost(addr *utils.NetAddr, newHost string) {
  	_, port, err := net.SplitHostPort(addr.Addr)
  	if err != nil {
  		log.Errorf("failed parsing address: '%v'", addr.Addr)
  	}
  	addr.Addr = net.JoinHostPort(newHost, port)
  }
docs: // replaceHost takes utils.NetAddr and replaces the hostname in it, preserving
  // the original port