_node p, void *item,
	       Ordertype (*compare) (void *, void *));
</B></PRE>Look for an item in an AVL tree.  That is, look for an item
for which the comparison function returns SAME_AS.  If it
is found, return the item in the tree; otherwise return NULL;
<A NAME="avl_height"></A><HR><PRE><B>int avl_height(Avl_node p);
</B></PRE>Return the height of an AVL tree.  Leaves have height 1.
<A NAME="avl_insert"></A><HR><PRE><B>Avl_node avl_insert(Avl_node p, void *item,
		    Ordertype (*compare) (void *, void