void->void pipeline Fib {
    add feedbackloop {
	join roundrobin(0, 1);
	body PeekAdd();
	loop Identity<int>();
	split duplicate;
	enqueue 0;
	enqueue 1;
    };
    add IntPrinter();
}

int->int filter PeekAdd {
    work push 1 pop 1 peek 2 {
	push(peek(1) + pop());
    }
}

int->void filter IntPrinter {
    work pop 1 {
	println(pop());
    }
}