anchor.diff:      if (reveals == null) {
         assert(game.state == GameState.lost);
   
  -      reveals = new Iterable.generate(game.field.length, (i) {
  +      reveals = new Iterable<Tuple>.generate(game.field.length, (i) {
           var t = game.field.getCoordinate(i);
           var c = new Point(t.item1, t.item2);
           return new Tuple(c, game.getSquareState(c.x, c.y));
  
positive.code:           .where((t2) =>
                t2.item2 == SquareState.bomb || t2.item2 == SquareState.hidden)
            .map((t2) => t2.item1)
            .toList();
      }
  
      final values = reveals.map((c) {
  
negative.code:                 return new Point(t.item1, t.item2);
                })
                .where((t) => game.getSquareState(t.x, t.y) == SquareState.hidden)
                .toList() as List<Point>;
  
            assert(adjHidden.length > 0);
  
  