code: func isURLOrHostPort(s string) bool {
  	return strings.HasPrefix(s, "http://") ||
  		strings.HasPrefix(s, "https://") ||
  		strings.Contains(s, ".") || strings.Contains(s, ":")
  }
docs: // isURLOrHostPort returns true if s looks like a URL, or a hostname, i.e it starts with a scheme and/or it contains a period or a colon.