anchor.diff:  class GridRenderer2D {
     CanvasRenderingContext2D canvas;
   
  -  String gold_color = "#FFD700";
  -   String white_color = "#FFFFFF";
  +  String gold_color =  "#FFD700";
  +  String white_color = "#FFFFFF";
  +
   
     static Coord snakePenSizeInPixels = new Coord(640, 480);
     static Coord gridBlockSizeInPixels = new Coord(10, 10);
  
positive.code:   }
  
    onRender(GameLoopHtml gameLoop) {
      canvas.clearRect(0, 0, snakePenSizeInPixels.getX(),
          snakePenSizeInPixels.getY());
      canvas.fillStyle = "rgb(255,165,0)";
      canvas.fillRect(0, 0, snakePenSizeInPixels.getX(),
          snakePenSizeInPixels.getY());
      canvas.font = "italic bold 24px sans-serif";
      canvas.strokeText("Inside snake pen", 0, 100);
  
  
negative.code:   }
  
    void clearCanvas() {
      fillCanvas(white_color);
    }
  
    void renderGridBlock(final Coord c, final String color) {
  