title: using stop-when in racket
body: <p>I've been messing around with this program. It takes a number and adds 1 to it. 
  I am wondering how exactly could you use <code>stop-when</code> here? For example, to make it stop at 5? I suppose a cond statement is necessary here. Thanks. </p>
  
  <pre><code>(require 2htdp/image)
  (require 2htdp/universe)
  
  (define (my-tick n)
  (add1 n))
  
  (define (my-render n)
    (text (number-&gt;string n) 36 "silver"))
  
  
  (big-bang 1 (on-tick my-tick 2) (to-draw my-render))
  </code></pre>