an class="special">&lt;</span><span class="identifier">A</span><span class="special">,</span> <span class="identifier">B</span><span class="special">...&gt;</span></code>
          as placeholders only. The notation of <code class="computeroutput"><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">A</span><span class="special">&gt;</span></code> stands for <span class="emphasis"><em>any <a href="https://en.wikipedia.org/wiki/Standard_Template_Library" target="_to