code: func CertificateSubjInTLD(c *x509.Certificate, label string) bool {
  	label = strings.ToLower(label)
  	if strings.HasPrefix(label, ".") {
  		label = label[1:]
  	}
  	if !IsInTLDMap(label) {
  		return false
  	}
  	for _, name := range append(c.DNSNames, c.Subject.CommonName) {
  		if strings.HasSuffix(name, "."+label) {
  			return true
  		}
  	}
  	return false
  }
docs: // CertificateSubjContainsTLD checks whether the provided Certificate has
  // a Subject Common Name or DNS Subject Alternate Name that ends in the provided
  // TLD label. If IsInTLDMap(label) returns false then CertificateSubjInTLD will
  // return false.