example in the docs

<%def name="layoutdata(somedata)">
    <table>
    % for item in somedata:
        <tr>
        % for col in item:
            <td>${caller.body(col=col)}</td>
        % endfor
        </tr>
    % endfor
    </table>
</%def>

<%self:layoutdata somedata="${[[1,2,3],[4,5,6],[7,8,9]]}" args="col">\
Body data: ${col}\
</%self:layoutdata>