template/funcs.go
func base64URLEncode(s string) (string, error) {
	return base64.URLEncoding.EncodeToString([]byte(s)), nil
}
func base64URLEncode(s string) (string, error) {
	return base64.URLEncoding.EncodeToString([]byte(s)), nil
}
// base64URLEncode encodes the given string to be URL-safe.