@Test
    public void testReturnTypes() {
        assertEquals(Integer.valueOf(4), __.__("test").length(Scope.local).next());
        assertArrayEquals(new Integer[]{5, 4, null, 0}, __.inject("hello", "test", null, "").length().toList().toArray());
        assertArrayEquals(new Integer[]{1, 2, 3}, ((List<?>) __.__(Arrays.asList("a", "bb", "ccc")).length(Scope.local).next()).toArray());
        assertArrayEquals(new Integer[]{5, 4, null, 0}, ((List<?>) __.__(Arrays.asList("hello", "test", null, "")).length(Scope.local).next()).toArray());
    }
@author Yang Xia (http://github.com/xiazcy)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/LengthLocalStepTest.java