Finding an element and adding a class to the previous one?

Finding an element and adding a class to the previous one?

Hi,

I have this menu:

<ul>
<li>Item 1</li>
<li>Item 2</li>
<li class="active">Item 3</li>
</ul>

..is it possible to find on which item is "active" set and give a class say "prev" to a class to the previous element (Item 2)?

Thanks!