public async Task ResultAsync(double value)
        {
            var action = new Protos.CalculatorDuplexCallback.Types.Result
            {
                Value = value,
            };

            var callback = new Protos.CalculatorDuplexCallback
            {
                Result = action
            };

            await _stream.WriteAsync(callback);
        }
 private async Task InvokeResultAsync(Protos.CalculatorDuplexCallback.Types.Result callback)
 {
     await _callback.ResultAsync(callback.Value);
 }