Totaly new in jquery here and I need a little help.

So I have one accordion menu which is working but I have to add one function. Now when I click on menu item is open properly but if doesn't close if I click again on the item. For example I have: 

1. Item1-head
2.  - sub-item1
3.  - sub-item2

I want when I click on item1-head to open and if I click again on item1-head to close. Now only is opening..

Here is the code

2.     $(document).ready(function () {
3.         $('#nav > li > a').click(function(e){
4.             if ($(this).attr('class') != 'active'){
5.                 $('#nav li ul').slideUp();
6.                 $(this).next().slideToggle();
7.                 $('#nav li a').removeClass('active');
8.                 $(this).addClass('active');
9.             }
10.             e.preventDefault();
11.         });
12.     });