digraph finite_automata {
 /* graph properties */
 graph [rankdir=LR label="hw3.fa"];
 node [style=filled fillcolor="#E0E0E0"];
 /* states */
 a [shape=circle];
 b [shape=circle];
 c [shape=doublecircle];
 invis_start [style=invis];
 /* transitions */
 invis_start -> a [label=" "];
 a -> b [label="1"];
 b -> b [label="0,1"];
 b -> c [label="0"];
}