code: func NewClientTLSConfig(certs []tls.Certificate, rootCAPool *x509.CertPool, serverName string) (*tls.Config, error) {
  	if rootCAPool == nil {
  		return nil, errors.New("valid root CA pool required")
  	}
  
  	return &tls.Config{
  		ServerName:   serverName,
  		Certificates: certs,
  		RootCAs:      rootCAPool,
  		MinVersion:   tls.VersionTLS12,
  	}, nil
  }
docs: // NewClientTLSConfig returns a tls.Config configured for a TLS Client, given a tls.Certificate
  // the PEM-encoded root CA Certificate, and the name of the remote server the client wants to connect to.