ifier">reduce</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">Histogram</span> <span class="special">&amp;</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">Iterable</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
      <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Histogram<span class="special">