[jQuery] noob question: how to close current visible <DD> in this script

[jQuery] noob question: how to close current visible <DD> in this script


Ladies and Gentlemen,
Here goes my complete noob question:
I have this demo page:
http://www.itchycloud.co.uk/panther/
in which I'm using this jquery script:
$(document).ready(function(){
        $("dd:not(:first)").hide();
        $("dt a").click(function(){
            $("dd:visible").slideUp("slow");
            $(this).parent().next().slideDown("slow");
            return false;
        });
    });
which I found on sniplr: http://snipplr.com/view/2208/jquery-collapsible-sidebar-menu/
I would like to modify this script so that when the user clicks on the
current active - displayed, open - <DT><A> then the appropriate <DD>
will collapse/hide.
I suppose it should be something like this in pseudo-code:
if current.DT is the previous sibling of current visible DD
then click function() will close DD;
else click function() will open next sibling DD
Basically, when there is a lot of content in a given DD I want the
user to be able to click on the previous sibling DT A and it will
close that DD. This will prevent a lot of scrolling with some pages on
the planned website.
TIA for your help. I am really looking forward to learning javascript
and jquery,
Adrian