1digraph invalid { 2 {node [shape = circle] "init"}; 3 {node [shape = circle] "state1"}; 4 "init" [label = "init"]; 5 "init" -> "state1" [ label = "event_a" ]; 6 "state1" [label = "state1"]; 7 "state1" -> "init" [ label = "event_b" ]; 8} 9