anchor.diff:        } else if (i < 8) {
           _modules[i + 1][8] = mod;
         } else {
  -        _modules[_moduleCount - 15 + i][8] = mod;
  +        _modules[moduleCount - 15 + i][8] = mod;
         }
       }
   
  
positive.code: 
      for (int i = 0; i < 18; i++) {
        final bool mod = (!test && ((bits >> i) & 1) == 1);
        _modules[i ~/ 3][i % 3 + _moduleCount - 8 - 3] = mod;
      }
  
      for (int i = 0; i < 18; i++) {
        final bool mod = (!test && ((bits >> i) & 1) == 1);
        _modules[i % 3 + _moduleCount - 8 - 3][i ~/ 3] = mod;
      }
    }
  
  
negative.code: 
      for (var r = -1; r <= 7; r++) {
  
        if (row + r <= -1 || moduleCount <= row + r) continue;
  
        for (var c = -1; c <= 7; c++) {
  
          if (col + c <= -1 || moduleCount <= col + c) continue;
  
          if ((0 <= r && r <= 6 && (c == 0 || c == 6)) ||
              (0 <= c && c <= 6 && (r == 0 || r == 6)) ||
  