private void OnEraseHistory(object sender, EventArgs e)
        {
            string message = "Do you want to clear the history?";
            string title   = "History Clear";

            if (String.IsNullOrEmpty(_history))
            {
                _messageBoxDisplayService.Show("The history is already empty!");
            }
            else
            {
                bool clearHistory = _messageBoxDisplayService.PromptUser(message, title);
                if (clearHistory)
                {
                    _history = "";
                    _calculatorView.SetHistoryBoxText(_history);
                }
            }
        }