digraph finite_state_machine {
    rankdir=LR;
    size="8,5"

    subgraph cluster_c2 {
        label="Accepting"; graph[style = dotted];
        node [shape = doublecircle];
        3 -> 4 [label = "i"];
        4 -> 3 [label = "o" constraint=false];
    }

    subgraph cluster_c1 {
        label="Non-accepting"; graph[style = dotted];
        node [shape = circle];
        0 -> 1 [label = "c"];
        1 -> 2 [label = "o"];
        2 -> 2 [label = "o"];
        2 -> 3 [label = "l"];
    }

    // Create an invisible point called START, so our starting state gets an arrow
    node [shape=point];
    START [style=invis];
    START -> 0;
}