title: how to toggle attr() in jquery
body: <p>I have a simple add attribute function:</p>
  
  <pre><code>$(".list-toggle").click(function() {
      $(".list-sort").attr('colspan', 6);
  });
  </code></pre>
  
  <p>My question is: how can I turn this into a toggle, so <code>colspan="6"</code> is removed from the element on the next click?</p>