private static void assertCommonA(final Traversal<Vertex, Tree> traversal) {
        final Tree tree = traversal.next();
        assertFalse(traversal.hasNext());
        assertEquals(1, tree.size());
        assertTrue(tree.containsKey("marko"));
        assertEquals(1, ((Map) tree.get("marko")).size());
        assertTrue(((Map) tree.get("marko")).containsKey("josh"));
        assertTrue(((Map) ((Map) tree.get("marko")).get("josh")).containsKey("lop"));
        assertTrue(((Map) ((Map) tree.get("marko")).get("josh")).containsKey("ripple"));
    }
@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