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