@Override
        public Traversal<Vertex, Map<Long, Long>> get_g_V_groupCount_byXbothE_countX() {
            return g.V().<Long>groupCount().by(bothE().count());
        }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/sideEffect/GroupCountTest.java