 tree.
If n is out of range, NULL is returned.
<A NAME="avl_place"></A><HR><PRE><B>int avl_place(Avl_node p, void *item,
	      Ordertype (*compare) (void *, void *));
</B></PRE>How far (counting from 1) from the beginning of the tree is the item.
If the item is not already in the tree, this function says how
far it would be if it were inserted first.
<A NAME="avl_position"></A><HR><PRE><B>double avl_position(Avl_node p, void *item,
		    Ordertype (*compare) (void *, void *));
</B></PRE>Return x, 0 < x <= 