code: func getTLSconfig() (*tls.Config, error) {
  	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
  	if err != nil {
  		return &tls.Config{}, err
  	}
  
  	return &tls.Config{
  		MinVersion:   tls.VersionSSL30,
  		MaxVersion:   tls.VersionTLS12,
  		Certificates: []tls.Certificate{cert},
  		ServerName:   "127.0.0.1",
  	}, nil
  }
docs: // getTLSconfig returns a tls configuration used
  // to build a TLSlistener for TLS or StartTLS