lass="identifier">iterator</span><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> Combiner<span class="special">&gt;</span> <a class="link" href="map.html" title="Class template map">map</a> <span class="special">&amp;</span> <a class="link" hre