template/funcs.go
func base64URLDecode(s string) (string, error) {
	v, err := base64.URLEncoding.DecodeString(s)
	if err != nil {
		return "", errors.Wrap(err, "base64URLDecode")
	}
	return string(v), nil
}
func base64URLDecode(s string) (string, error) {
	v, err := base64.URLEncoding.DecodeString(s)
	if err != nil {
		return "", errors.Wrap(err, "base64URLDecode")
	}
	return string(v), nil
}
// base64URLDecode decodes the given string as a URL-safe base64 string.