digraph g {
	subgraph a {
		Start [shape=box];
		End [shape=box];
		f [label=<f (a, b)>]
		Start -> "a = 10" -> "b = 20" -> f -> End;
	}
	subgraph b {
		s [shape=box,label=<Start>];
			End2 [shape=box,label=<End>];
			s -> "while (x > y)" -> "x = x - 1" -> "while (x > y)" -> "print(x)" -> End2;
	}
}