,</span> <span class="keyword">class</span><span class="special">...</span> Ts<span class="special">&gt;</span> 
        <span class="keyword">decltype</span><span class="special">(</span><span class="keyword">auto</span><span class="special">)</span> 
        <a class="link" href="../boost/histogram/algorithm/reduce_idm45105995165776.html" title="Function template reduce"><span class="identifier">reduce</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">Hist