Why is an object sent into this function, but is never used?
<pre><code>int height(const Tree&amp; T, const Position&amp; p) {
    if (p.isExternal()) return 0;       // leaf has height 0
    int h = 0;
    PositionList ch = p.children();     // list of children
    for (Iterator q = ch.begin(); q != ch.end(); ++q)
      h = max(h, height(T, *q));
    return 1 + h;               // 1 + max height of children
  }
</code></pre>

<p>My textbook gives the above code for finding the height of a general tree. Why is "Tree T" sent into the function if it is never used (its member functions/variables never called or used) throughout the function?</p>
