Moving a sprite around the screen

Now that we have the George sprite animating, we will build on that and change the animation based on the direction of travel:

1. Let's add some variables at the top of the George class to store the animations and direction information:

     late SpriteAnimation georgeDownAnimation, 
       georgeLeftAnimation, georgeUpAnimation, 
       georgeRightAnimation;
     double elapsedTime = 0.0;
     double georgeSpeed = 40.0;
     int currentDirection = down;
     static const int down = 0, left = 1, up = 2, 
       right = 3;

2. Below the onLoad function, define a new function called changeDirection, which we will call every 3 seconds to change George's direction randomly:

     void changeDirection() {
       Random random = Random();
       int newDirection = random.nextInt(4);
       switch (newDirection...