* @return the "Dot" graph definition
*/
public String graph() throws Exception {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
PrintWriter out = new PrintWriter(baos);
Injector localInjector = Guice.createInjector(new GrapherModule(), new GraphvizModule());
GraphvizRenderer renderer = localInjector.getInstance(GraphvizRenderer.class);
renderer.setOut(out).setRankdir("TB");
InjectorGrapher g = localInjector.getInstance(InjectorGrapher.class).of(injector);
if (roots != null) {
g.rootedAt(roots);