@Test
    @LoadGraphWith(MODERN)
    public void g_V_out_tree_byXageX() {
        final Traversal<Vertex, Tree> traversal = get_g_V_out_tree_byXageX();
        printTraversalForm(traversal);

        final Tree tree = traversal.next();
        assertFalse(traversal.hasNext());
        assertEquals(3, tree.size());
        assertTrue(tree.containsKey(29));
        assertEquals(2, ((Map) tree.get(29)).size());
        assertTrue(((Map) tree.get(29)).containsKey(32));
        assertTrue(((Map) tree.get(29)).containsKey(27));
        assertTrue(tree.containsKey(35));
        assertEquals(0, ((Map) tree.get(35)).size());
        assertTrue(tree.containsKey(32));
        assertEquals(0, ((Map) tree.get(32)).size());
    }
@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