ifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&gt;</span> <span class="identifier">x</span><span class="special">;</span>
  <span class="identifier">x</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="string">"hello"</span><span class="special">);</span>
  <span class="identifier">x</span><span class="special">.</span><span class="identifier">push_back</span><span class="specia