gistfile1.dot

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

    start [shape = doublecircle];
    number [shape = circle];
    operator [shape = circle];
    end [shape = doublecircle];

    start -> number [label=digit];
    number -> number [label=digit];
    number -> start [label="!digit"];
    start -> operator [label=otherwise];
    operator -> start [];
    start -> end [label=eof];
}