>&amp;</span> header<span class="special">)</span><span class="special">;</span></pre>
<p><span class="bold"><strong>Requires</strong></span>: node is a node of the tree but it's not the header.</p>
<p><span class="bold"><strong>Effects</strong></span>: Returns the number of nodes of the subtree.</p>
<p><span class="bold"><strong>Complexity</strong></span>: Linear time.</p>
<p><span class="bold"><strong>Throws</strong></span>: Nothing. </p>
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