code: func (c *Client) BatchCall(b []BatchElem) error {
  	ctx := context.Background()
  	return c.BatchCallContext(ctx, b)
  }
docs: // BatchCall sends all given requests as a single batch and waits for the server
  // to return a response for all of them.
  //
  // In contrast to Call, BatchCall only returns I/O errors. Any error specific to
  // a request is reported through the Error field of the corresponding BatchElem.
  //
  // Note that batch calls may not be executed atomically on the server side.