ial">(</span><span class="identifier">node_ptr</span> header<span class="special">)</span><span class="special">;</span></pre>
<p><span class="bold"><strong>Requires</strong></span>: node must not be part of any tree.</p>
<p><span class="bold"><strong>Effects</strong></span>: Initializes the header to represent an empty tree. unique(header) == true.</p>
<p><span class="bold"><strong>Complexity</strong></span>: Constant.</p>
<p><span class="bold"><strong>Throws</strong></span>: Nothing.</p>
<p><span class="b