code: func IsLoopback(host string) bool {
  	if strings.Contains(host, ":") {
  		var err error
  		host, _, err = net.SplitHostPort(host)
  		if err != nil {
  			return false
  		}
  	}
  	ips, err := net.LookupIP(host)
  	if err != nil {
  		return false
  	}
  	for _, ip := range ips {
  		if ip.IsLoopback() {
  			return true
  		}
  	}
  	return false
  }
docs: // IsLoopback returns 'true' if a given hostname resolves to local
  // host's loopback interface