anchor.diff:  
     // Detect if we're outside the playing board.
     bool isOnCanvas(Coord coord) {
  -    return (coord.x >= 0 && coord.y >= 0 && coord.x <= cowidth && coord.y <=
  -        coheight);
  +    return (coord.x >= 0 && coord.y >= 0 && coord.x <= width && coord.y <=
  +        height);
     }
   
   
  
positive.code:   int maxSize = 3;
    List<Coord> coords = new List();
  
    int cowidth;
    int coheight;
  
    int points = 5;
  
  
negative.code: 
    Snake(int w, int h) {
  
      width = w;
      height = h;
  
      coords.add(newRandomCoord());
      assert(coords.length == 1);
    }
  
    Coord newRandomCoord() {
      return new Coord(rnd.nextInt(width), rnd.nextInt(height));
    }
  
    void addPoints(num delta) {
  