borg/docs/_templates/globaltoc.html

<div class="sidebar-block">
  <div class="sidebar-toc">
    {% set toctree = toctree(maxdepth=3, collapse=True, includehidden=True) %}
    {% if toctree %}
      {{ toctree }}
    {% else %}
      {{ toc }}
    {% endif %}
  </div>
</div>