I just ran into this script today and I don't know what this really does. I'm not sure what this is. It looks like an anonymous function that has a function within a function that calls a function but when I test this it actually just prints to the screen "function wtf(){document.write(wtf)} ;"

I'm confused here. Any help would be appreciated. Thanks!

Code:
<script type="text/javascript">
	//<![CDATA[
	(
		function() 
		{
			function wtf() 
			{ 
				document.write(wtf);
			}
			wtf();
		}
	)();
	//]]>
</script>