function tuple(var bool, var int): int_plus(
	tuple(var bool, var int): x,
	tuple(var bool, var int): y
) =
	let {
		(x1, x2) = x;
		(y1, y2) = y;
		var int: x3 = if_then_else([x1, true], [x2, 0]);
		var int: y3 = if_then_else([y1, true], [y2, 0]);
		tuple(var bool, var int): res = (bool_and(x1, y1), int_plus(x3, y3));
	} in res;