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