anchor.diff:  }
   
   class _DatePickerDialogState extends State<_DatePickerDialog> {
  -  bool _vibrate = false;
  -
     @override
     void initState() {
       super.initState();
  
positive.code:   _DatePickerMode _mode = _DatePickerMode.day;
    GlobalKey _pickerKey = new GlobalKey();
  
    void _handleModeChanged(_DatePickerMode mode) {
      if (_vibrate)
        HapticFeedback.vibrate();
      setState(() {
        _mode = mode;
      });
    }
  
    void _handleYearChanged(DateTime value) {
      if (_vibrate)
        HapticFeedback.vibrate();
      setState(() {
        _mode = _DatePickerMode.day;
        _selectedDate = value;
  
negative.code:   }
  
    void _handleDayChanged(DateTime value) {
      _vibrate();
      setState(() {
        _selectedDate = value;
      });
  