Slide animate list

Hello

I have this a where I want to slide every li to the left when i click on #btn. Like it is done in http://sorgalla.com/projects/jcarousel/examples/static_simple.html .

<ul id="thelist">
<li></li>
<li></li>
<li></li>
<li></li>
</ul>

<a id="btn" href="#">btn</a>

Do you know how to do that ?