Graphviz and Finite Automata diagrams

Graphviz is a freeware application developed to draw diagrams for given specification. This specification or language is easier to understand, so easier to program (or specify).
 Graphviz is a collection of utilities, for different types of graphs. For the Finite automata diagrams, dot is used for directed graphs type. There is a specification for finite automata.

and the specification for that is shown below.
digraph finite_state_machine {
    rankdir=LR;
      node [shape = point, color=white, fontcolor=white]; start;
    node [shape = doublecircle, color=black, fontcolor=black]; q2;
    node [shape = circle]; q1;
    start -> q1;
      q1 -> q1 [ label = "0" ];
    q1 -> q2 [ label = "1" ];
    q2 -> q3 [ label = "1" ];
      q2 -> q3 [ label = "0" ];
      q3 -> q2 [ label = "0,1" ];
}