@Test
    @LoadGraphWith(MODERN)
    public void g_V_age_sum() {
        final Traversal<Vertex, Number> traversal = get_g_V_age_sum();
        printTraversalForm(traversal);
        final Number sum = traversal.next();
        assertEquals(123, sum.intValue());
        assertFalse(traversal.hasNext());
    }
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/SumTest.java