digraph G {subgraph cluster_0 {style=filled;color=lightgrey;node [style=filled,color=white];a0 -> a1 -> a2 -> a3;label = "process #1";}subgraph cluster_1 {node [style=filled];b0 -> b1 -> b2 -> b3;label = "process #2";color=blue}start -> a0;start -> b0;a1 -> b3;b2 -> a3;a3 -> a0;a3 -> end;b3 -> end;start [shape=Mdiamond];end [shape=Msquare];}