(fun() {
	## test return variables

	| v1 v2 v3 i a b c d |

	set i 100;

	defun ff(a b :: x y z) {
		set x (+ a b i);
		set y (+ x x);
		set z (+ 999 i);
		set i (* i 10);
	};

	set-r v1 v2 v3 (ff 10 20);
	if (/= v1 130) { printf "ERROR: v1 must be 130\n" };
	if (/= v2 260) { printf "ERROR: v2 must be 260\n" };
	if (/= v3 1099) { printf "ERROR: v3 must be 1099\n" };
	printf "OK v1=%d v2=%d v3=%d\n" v1 v2 v3;

	set-r v1 v2 (ff 1 2); ## using 2 return variables only. not assigning to v3
	if (/= v1 1003) { printf "ERROR: v1 must be 1003\n" };
	if (/= v2 2006) { printf "ERROR: v2 must be 2006\n" };
	if (/= v3 1099) { printf "ERROR: v3 must be 1099\n" };
	printf "OK v1=%d v2=%d v3=%d\n" v1 v2 v3;


	## test return variables in message sends
	defclass B [ [X1 X2] ] {

		set X1 999;
		set X2 888;

		defun :: get ( :: x y)  {
			set x X1;
			set y X2;
		};

		defun :: get2 (inc :: x y)  {
			set x (+ X1 inc);
			set y (+ X2 inc);
		};
	};

	set-r a b (B:get);
	set-r c d (B:get2 -100);

	if (/= a 999) { printf "ERROR: a must be 999\n" };
	if (/= b 888) { printf "ERROR: b must be 888\n" };
	if (/= c 899) { printf "ERROR: c must be 899\n" };
	if (/= d 788) { printf "ERROR: d must be 788\n" };

	printf "OK a=%d b=%d c=%d d=%d\n" a b c d;

	class X [ x, y ] {
		fun ::f(a :: b c) { b := (a + 10); c := (a + 20) }

		fun :*new(z) {
			## multi-variable assignment with return variables to member variables
			[self.x, self.y] := (X:f z)
			return self;
		}

		fun getX() { return self.x }
		fun getY() { return self.y }
	}

	z := (X:new 9)
	if ((x := (z:getX)) /= 19) { printf "ERROR: z:getX msut return 19\n" }
	if ((y := (z:getY)) /= 29) { printf "ERROR: z:getX msut return 29\n" }
	printf "OK z:getX=%d z:getY=%d\n" x y
});