code: func (probe *GrpcHealthProbe) Check() error {
  	ctx, cancel := context.WithTimeout(context.Background(), probe.timeout)
  	defer cancel()
  
  	connection, err := grpc.DialContext(ctx, probe.server, probe.dialOptions...)
  	if err != nil {
  		return err
  	}
  	defer connection.Close()
  
  	client := hv1.NewHealthClient(connection)
  	response, err := client.Check(ctx, probe.request)
  	if err != nil {
  		return err
  	}
  	if response == nil || (response != nil && response.Status != hv1.HealthCheckResponse_SERVING) {
  		return ErrGRPCUnhealthy
  	}
  
  	return nil
  }
docs: // Check if the target of this GrpcHealthProbe is healthy
  // If nil is returned, target is healthy, otherwise target is not healthy