s="keyword">struct</span> <a class="link" href="tail_mean.html" title="Struct tail_mean">tail_mean</a> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">accumulators</span><span class="special">::</span><span class="identifier">depends_on</span><span class="special">&lt;</span><span class="special">&gt;</span> <span class="special">{</span>
  <span class="comment">// types</span>
  <span class="keyw