@Override
    public boolean add(String e) {
        return get(addAsync(e));
    }
@Test
    public void testFirstLast() {
        RLexSortedSet set = redisson.getLexSortedSet("simple");
        set.add("a");
        set.add("b");
        set.add("c");
        set.add("d");

        Assertions.assertEquals("a", set.first());
        Assertions.assertEquals("d", set.last());
    }