anchor.diff:    static final List<String> level4 =
     [ 'LIIIL',
       'v...I',
  -    'ILIPT',
  +    'ILIpT',
       'II..J',
  -    'LTPIL' ];
  +    'LTpIL' ];
     static final List<String> level5 =
     [ 'L....L.',
       'LIIPITL',
  
positive.code: class LevelData {
  
    static final List<String> level1 =
    [ 'LIP',
      'I I',
      'L>L' ];
    static final List<String> level2 =
  
negative.code:     'JLLTBLL',
      'LTLLT^.',
      '.LIJIL.' ];
    static final List<String> level6 =
    [ 'LILLIL.',
      'ILTLISL',
      'TBLpILI',
      'IILI.LT',
      'L>TL.PL',
      'L.LTIL.' ];
  
    static Level loadLevel(List<String> data) {
      int width = data[0].length;
  