title: How do I use Scriptaculous's Effect.Morph to turn off a class?
body: <p>Scriptaculous's Effect.Morph can take a CSS class and apply it over a period of time.  I have a div which expands when a button is clicked, so it uses Effect.Morph to apply an <code>.expanded</code> class.</p>
  
  <p>Now I'd like to remove the <code>.expanded</code> class on a second click, toggling the div closed again.  How can I invoke Effect.Morph to do that?</p>