anchor.diff:  
     final typeNumber;
     final errorCorrectLevel;
  -  final int _moduleCount;
  +  final int moduleCount;
     final List<List> _modules;
     List<int> _dataCache;
     List<QrByte> _dataList;
   
     QrCode(int tn, this.errorCorrectLevel)
     : typeNumber = tn,
  -  _moduleCount = tn * 4 + 17,
  +  moduleCount = tn * 4 + 17,
     _modules = new List<List<bool>>() {
       requireArgument(typeNumber > 0 && typeNumber < 11, 'tn');
   
  -    for (var row = 0; row < _moduleCount; row++) {
  -      _modules.add(new List<bool>(_moduleCount));
  +    for (var row = 0; row < moduleCount; row++) {
  +      _modules.add(new List<bool>(moduleCount));
       }
   
       _dataCache = null;
  
positive.code:   void _makeImpl(bool test, int maskPattern) {
  
      _setupPositionProbePattern(0, 0);
      _setupPositionProbePattern(_moduleCount - 7, 0);
      _setupPositionProbePattern(0, _moduleCount - 7);
      _setupPositionAdjustPattern();
      _setupTimingPattern();
      _setupTypeInfo(test, maskPattern);
  
negative.code: 
          row += inc;
  
          if (row < 0 || moduleCount <= row) {
            row -= inc;
            inc = -inc;
            break;
  