<ul tal:condition="python:here.public_subtopics is not []">
    <span tal:repeat="item here/public_subtopics">
    <li ><a tal:content="item/title_or_id" tal:attributes="href item/absolute_url">Title</a></li>
    <span tal:replace="structure item/list_subtopics" />
    </span>
</ul>