public static <T> List<T>
	sub(List<T> list, int start, int end) {
		return sub(list, start, end, 1);
	}
@Test
	public void subTest() {
		final List<Integer> of = ListUtil.of(1, 2, 3, 4);
		final List<Integer> sub = ListUtil.sub(of, 2, 4);
		sub.remove(0);

		// 对子列表操作不影响原列表
		assertEquals(4, of.size());
		assertEquals(1, sub.size());
	}