f="map.html#id673666-bb"><span class="identifier">_subtract</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">element_type</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> FragmentT<span class="special">&gt;</span> 
    <span class="keyword">void</span> <a class="link" href="map.html#id673686-bb"><