ecial">(</span><span class="keyword">const</span> <span class="identifier">const_node_ptr</span> <span class="special">&amp;</span> header<span class="special">)</span><span class="special">;</span></pre>
<p><span class="bold"><strong>Requires</strong></span>: 'header' is the header node of a tree.</p>
<p><span class="bold"><strong>Effects</strong></span>: Returns the first node of the tree, the header if the tree is empty.</p>
<p><span class="bold"><strong>Complexity</strong></span>: Constant time.</p>
<p>