List
StateChart
Dotscript
digraph finite_state_machine {
rankdir = LR;
node [shape = circle]; 0;
node [shape = doublecircle]; 2;
node [shape = plaintext];
"" -> 0 [label = "start"];
node [shape = circle];
0->1 [label="a"];
1->2 [label="b"];
}