digraph hierarchy {
	subgraph cluster_1 {
		label="top level"
		top [label="top sheet" shape=box]
	}

	an [shape=box]
	dig [shape=box]

	top -> dig
	top -> an
	an -> amp1
	an -> amp2
	an -> amp3
	an -> amp4

	amp1 [label="amp" shape=box]
	amp2 [label="amp" shape=box]
	amp3 [label="amp" shape=box]
	amp4 [label="amp" shape=box]
}
