s spouses and arrows point to children.</b></center></figcaption>
</figure>
</p>
    </div>
</div>

<p><br /></p>

<div class="card">
    <div class="card-header p-2">
        <a href="ex_18/" class="p-2">Exercise 18 </a>
        <button type="button" class="btn btn-dark float-right" title="Bookmark Exercise" onclick="bookmark('ch8ex18');" href="#"><i id="ch8ex18" class="fas fa-bookmark" style="color:white"></i></button>
        <button type="button" class="btn btn-dark float-right" style="margin-left:10px;