@Test
    @LoadGraphWith(MODERN)
    public void g_V() {
        final Traversal<Vertex, Vertex> traversal = get_g_V();
        printTraversalForm(traversal);
        int counter = 0;
        final Set<Vertex> vertices = new HashSet<>();
        while (traversal.hasNext()) {
            counter++;
            vertices.add(traversal.next());
        }
        assertEquals(6, vertices.size());
        assertEquals(6, counter);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/VertexTest.java