declare
class BallGame
   attr other count:0
   meth init(Other)
      other:=Other
   end
   meth ball
      count:=@count+1
      {@other ball}
   end
   meth get(X)
      X=@count
   end
end

B1={NewActive BallGame init(B2)}
B2={NewActive BallGame init(B1)}
{B1 ball}