;; Bounce a single ball around the screen.

; For this problem set you must complete the design of a world program.

;; The complete program must have the following behaviour:

;; $-$ there is a green background, with a single white ball

;; bouncing around inside that box

;; $-$ when the ball hits the top$/$right$/$bottom$/$left of the box it

;; bounces in the usual way a ball would bounce off of a wall

;; $-$ clicking the mouse replaces the ball with a new ball, at the

;; current mouse position, and with a small random x$,$y velocity

;;

;; Note that we are giving you significant help in the starter file.

;; There is a complete data design, some complete helper functions, as

;; well as a some wish list entries. You absolutely MUST

;; $-$ not edit any of the complete design elements we give you

;; $-$ complete the wish list entries we give you, and do so in a way

;; that is consistent with the rest of the design we give you

;; $-$ must use the helpers we give you as part of your solution

;;

;; We recommend that you begin by first going through the entire file to

;; understand what is already complete and what you need to complete.

;;