code: func splitHostPort(hostport string) (string, string, error) {
  	if strings.Contains(hostport, ":") {
  		return net.SplitHostPort(hostport)
  	} else {
  		return hostport, "", nil
  	}
  }
docs: // splitHostPort wraps net.SplitHostPort, and can be called on a host
  // whether or not it contains a port segment.