/* Initializes |trav| for |tree|.
   Returns data item in |tree| with the greatest value,
   or |NULL| if |tree| is empty. */
void *
pbst_t_last (struct pbst_traverser *trav, struct pbst_table *tree)
{
  assert (tree != NULL && trav != NULL);

  trav->pbst_table = tree;
  trav->pbst_node = tree->pbst_root;
  if (trav->pbst_node != NULL)
    {
      while (trav->pbst_node->pbst_link[1] != NULL)
        trav->pbst_node = trav->pbst_node->pbst_link[1];
      return trav->pbst_node->pbst_data;
    }
  else
    return NULL;
}