code: func (c *GRPCClient) Ping() error {
  	client := grpc_health_v1.NewHealthClient(c.Conn)
  	_, err := client.Check(context.Background(), &grpc_health_v1.HealthCheckRequest{
  		Service: GRPCServiceName,
  	})
  
  	return err
  }
docs: // ClientProtocol impl.