SO? comment demo: What code do i need to collapse a div when another is open?

http://stackoverflow.com/questions/5148075/what-code-do-i-need-to-collapse-a-div-when-another-is-open/5148190#5148190

HTML

<div class="category">A
    <ul class="artists"><li>Apple</li><li>Ace</li><li>Ants</li></ul>
</div>
<div class="category firstShown">B
    <ul class="artists"><li>Bee</li><li>Bop</li><li>Book</li></ul>
</div>
<div class="category">C
    <ul class="artists"><li>Cake</li><li>Chimp</li><li>Charles</li></ul>
</div>


<!--Simple Implementation and dependancies-->
<a id="prev" href="#">Prev</a>
<a id="next" href="#">Next</a>
<a href="#2">2</a>

CSS

div { width: 300px; margin-bottom: 30px; cursor: pointer; }
.category { background: lightblue; }
.artists { margin-left: 30px; display: none; }

div > div {
 font-size:5em;
 width:auto;
 text-align:center;
 padding:20px 0;   
 display:none;
}

JavaScript

$(".category").click(function() {
    $(this).children(".artists").show();
    $(this).siblings(".category").find(".artists").hide();
}).filter(".firstShown").click();

$(function(){
    //Reference Object
    var $divs = $('div > div');
    //Buffer for selected variable
    var $selected = 0;
    //Show first
    $divs.eq(0).show();
    
    
    $('#next').click(function(){
        //Update selected var
         $selected = $divs.filter(':visible');
        //Save next to variable
        var $next = $selected.next();
        //Change Visibility
        toggle($next);
        //Prevent Default
        return false;
    });
    
     $('#prev').click(function(){
        $selected = $divs.filter(':visible');
        var $prev = $selected.prev();
        toggle($prev);
        return false;
    });
    
    $('a').click(function(){
        $selected = $divs.filter(':visible');
        var selector = $(this).attr('href');
        if(selector == '#') return false;
        toggle( $( selector ) );
        return false;
    });
   

    var toggle = function($toggle){
     if(!$toggle.length) return false;
         $selected.hide();
         //for fun
         $toggle.fadeIn();  
         //$toggle.show();   
     }
        });