class="special">.</span><span class="identifier">end</span><span class="special">();</span>
    <span class="special">}</span>

    <span class="comment">// extension to populate</span>
    <span class="keyword">void</span> <span class="identifier">add</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">ep</span><span class="special">)</span> <span class="special">{</span>
        <span 