span class="comment">// create a container of boxes</span>
    <span class="identifier">container</span> <span class="identifier">boxes</span><span class="special">;</span>
    <span class="keyword">for</span> <span class="special">(</span> <span class="identifier">size_type</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span> <span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="number">10</span> <spa