##       Software from the book "Inferno Programming with Limbo"#       published by John Wiley & Sons, January 2003.##       p. Stanley-Marbell <pip@gemusehaken.org>#implement Cyclic; include "sys.m";include "draw.m"; Cyclic : module{	init : fn (nil : ref Draw->Context, nil : list of string);}; Tree : adt{	child : cyclic ref Leaf;}; Leaf : adt{	parent : ref Tree;};	 init (nil : ref Draw->Context, nil : list of string){	tree : Tree;	leaf : Leaf; 	tree.child = ref leaf;}