types
  Class1 = autocons system
  |[
  var
	O2 : Class2 = new (Class2);
	O3 : Class3 = new (Class3);
	OL : list[2] of Class2 = [nil]
  actions
	ctr fill = requires true :
		OL := [O2]^[O3 as Class2]
		end
  do
        fill
  od
  ]| ;
  Class2 = system
  |[
  ]| ;
  Class3 = system (Class2)
  |[
  ]| 
system
        Class1