anchor.diff:    TileType get floor => Tiles.floor;
     TileType get wall => Tiles.wall;
   
  -  Dungeon()
  -    : _rooms = <Room>[],
  -      _usedColors = new Set<int>();
  +  Dungeon();
   
     void generate(Stage stage) {
       bindStage(stage);
  
positive.code:   }
  
    /// Places a table in the room.
    bool decorateTable(Rect room) {
      var pos = rng.vecInRect(room);
  
      // Don't block an exit.
  
negative.code:     }
    }
  
    void _decorateRooms(void decorateRoom(Rect room)) {
      for (var i = 0; i < _rooms.length; i++) {
        var room = _rooms[i];
  
        // Don't decorate overlapping rooms.
        var overlap = false;
  