e class="synopsis"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">histogram</span> <span class="special">{</span>
    <span class="keyword">namespace</span> <span class="identifier">algorithm</span> <span class="special">{</span>
      <span class="keyword">struct</span> <a class="link" href="../boost/histogram/algorithm/reduce_option.html" title="Struct reduce_option">reduce_option