html#idm14177-bb"><span class="identifier">bin</span></a><span class="special">(</span><span class="identifier">index_type</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="identifier">index_type</span> <a class="link" href="category.html#idm14182-bb"><span class="identifier">size</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special