node diagonal_int (i: int) returns (o1, o2 : int);
let
	(o1, o2) = (i, i);
tel

node undiag_test (i: int) returns (o : bool);
var l1, l2: int; l3: int;
let
	l3 = (pre (1)) -> 0;
	(l1, l2) = diagonal_int(i);
	o = (not (not (l1 = l2))) and (l1 = l2) and true;
tel

node auto (i: int) returns (o : int);
var x, y:int;
let
	automaton
	| Incr -> do (o,x) = (0 fby o + 1, 2); done
	| Decr -> do (o,x) = diagonal_int(0 fby o); done
tel