code: func (rootCA *RootCA) NewClientTLSCredentials(cert *tls.Certificate, serverName string) (*MutableTLSCreds, error) {
  	tlsConfig, err := NewClientTLSConfig([]tls.Certificate{*cert}, rootCA.Pool, serverName)
  	if err != nil {
  		return nil, err
  	}
  
  	mtls, err := NewMutableTLS(tlsConfig)
  
  	return mtls, err
  }
docs: // NewClientTLSCredentials returns GRPC credentials for a TLS GRPC client, given a tls.Certificate
  // a PEM-Encoded root CA Certificate, and the name of the remote server the client wants to connect to.