p36255408-bb"><span class="identifier">flat_map</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">flat_map</span><span class="special">&lt;</span> <span class="identifier">Key</span><span class="special">,</span> <span class="identifier">T</span> <span class="special">&gt;</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  <span class="identifier">flat_map</span><span class="special">&lt;</span> <span clas