[web2py] Navigation in Web2py having an active link

[ADE]

Hello I am trying to figure out how to check if the current page is
active in web2py

I have my navigation as follows

        <ul>
            <li><a href="{{=URL('default', 'index')}}">Home</a></li>
            <li><a href="{{=URL('view', 'schedule')}}">What's On</a></
li>
            <li><a href="{{=URL('default', 'about')}}">About PSTV</a></
li>
            <li><a href="{{=URL('blog', 'index')}}">Blog</a></li>
            <li><a href="{{=URL('view', 'categories')}}">Episodes</a></
li>
            <li><a href="{{=URL('view', 'trailers')}}">Trailers</a></
li>
            <li><a href="http://shop.pstv.tv";>Shop</a></li>
            <li><a href="{{=URL('default', 'contact')}}">Contact Us</
a></li>
        </ul>

if the current page is active I would like to set <li> to <li
class="selected">

Any ideas how to do this

*cheers