e="Class template unordered_set_base_hook">unordered_set_base_hook</a> <span class="special">:</span>
  <span class="keyword">public</span> <span class="identifier">make_unordered_set_base_hook</span><span class="special">::</span><span class="identifier">type</span><span class="special">&lt;</span> <span class="identifier">O1</span><span class="special">,</span> <span class="identifier">O2</span><span class="special">,</span> <span class="identifier">O3</span><span class="special">,</span> <span class="ide