#w base.mako   :
#w head:
    <%def name="jsfile()">
        ${caller.body()}
    </%def>
</head>

#base.mako w body:

     <%def name="content_title()">
                ${caller.body()}
            </%def>
            ${next.body()}

#w mean_time_weekday.html:

<%inherit file="base.mako"/>
<%namespace name="foo" file="library.mako"/>

<%foo:static_files>

</%foo:static_files>

<%call expr="jsfile()">
    <script type="text/javascript" src="static/js/mean_time.js"></script>
</%call>

<%call expr="content_title()">
   Presence mean time by weekday
</%call>