t<span class="special">&gt;</span> 
  <a name="idm14219-bb"></a><span class="identifier">category</span><span class="special">(</span><span class="identifier">It</span> begin<span class="special">,</span> <span class="identifier">It</span> end<span class="special">,</span> <span class="identifier">metadata_type</span> meta <span class="special">=</span> <span class="special">{</span><span class="special">}</span><span class="special">,</span> 
           <span class="identifier">allocator_type</span> alloc 