an> <span class="number">8U</span><span class="special">;</span> <span class="identifier">k</span><span class="special">++)</span>
   <span class="special">{</span>
      <span class="identifier">h</span> <span class="special">/=</span> <span class="number">2</span><span class="special">;</span>

      <span class="identifier">value_type</span> <span class="identifier">sum</span><span class="special">(</span><span class="number">0</span><span class="special">);</span>
      <span class="keyword">for</span><