mp;</span><span class="special">)</span><span class="special">;</span>
  <a class="link" href="map.html" title="Class template map">map</a> <span class="special">&amp;</span> <a class="link" href="map.html#id673296-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>
  <a class="link" href="map.html" title="Cla