code: func verifyAud(aud string, cmp string, required bool) bool {
  	if aud == "" {
  		return !required
  	}
  	if subtle.ConstantTimeCompare([]byte(aud), []byte(cmp)) != 0 {
  		return true
  	} else {
  		return false
  	}
  }
docs: // ----- helpers