[jQuery] The simplest of questions I'm sure...

[jQuery] The simplest of questions I'm sure...


I'm brand new to jquery, and I need a little help with this simple
accordion menu code:
$(document).ready(function(){
        $("dd:not(:first)").hide();
        $("dt a").click(function(){
            $("dd:visible)").slideUp("slow");
            $(this).parent().next().slideDown("slow");
            return false;
        });
});
The html is like this:
<dt><a href="/">Section</a></dt>
<dd>
<ul>
     <li><a href="url">Item</a></li>
And so on...
It works nicely, but I don't know how to make it so that when you
click on a section title that is ALREADY open, it will close instead.
At the moment, it will close and then slide open again.
I'm sure there's a simple condition that will fix it, but I'm shooting
in the dark at the moment and can't seem to do it.
Any help much appreciated.