@Test
    @LoadGraphWith(MODERN)
    public void g_V_out_out_out_tree() {
        final Traversal<Vertex, Tree> traversal = get_g_V_out_out_out_tree();
        printTraversalForm(traversal);
        final Tree tree = traversal.next();
        assertTrue(tree.isEmpty());
        assertFalse(traversal.hasNext());
    }
@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/TreeTest.java