createVertex('Entity');
$a->setAttribute('graphviz.shape', 'none');
$a->setAttribute('graphviz.label', GraphViz::raw('<
>'));
$b = $graph->createVertex('Block');
$b->createEdgeTo($a);
$b->setAttribute('graphviz.shape', 'none');
$b->setAttribute('graphviz.label', GraphViz::raw('<
>'));
$graphviz = new GraphViz();
echo $graphviz->createScript($graph);
$graphviz->display($graph);