title: Can a tree node be both a root node and a leaf node?
body: <p>Can a tree node be both a root node and leaf node? If so, why?</p>
  <p>I understand that the root node is at Level 0 of the tree. I also understand that a leaf node is a tree node that has no children. So if a tree has a root node <code>A</code> and nothing else, would that root node <code>A</code> also be considered a leaf node?</p>
  <p>Is it possible for a tree node to be both a root node and leaf node?</p>