ss="special">::</span><span class="identifier">first_type</span> <span class="special">&amp;</span> <a class="link" href="first.html#idp89317936-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">Pair</span> <span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">template</span><span class="special">&lt;