@Override
    protected List<Traversal> getTraversals() {
        return Arrays.asList(
                __.group().by(T.label),
                __.group().by(T.label).by("name"),
                __.group().by(T.label).by(__.values("name").count())
        );
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/GroupStepTest.java