### Question:
RList extends RCollection { public void delTtl(String key) throws KitDBException { checkTxStart(); try (CloseLock ignored = checkClose()) { byte[] key_b = getKey(key); MetaV metaV = getMeta(key_b); if (metaV == null) { checkTxCommit(); return; } LockEntity lockEntity = lock(key); try { start(); delTimerCollection(KeyEnum.COLLECT_TIMER, metaV.getTimestamp(), key_b, metaV.convertMetaBytes().toBytesHead()); metaV.setTimestamp(-1); putDB(key_b, metaV.convertMetaBytes().toBytes(), SstColumnFamily.META); commit(); } finally { unlock(lockEntity); release(); } checkTxCommit(); } catch (Exception e) { checkTxRollBack(); throw e; } } protected  RList(DB db); void add(String key, byte[] v); void addAll(String key, List<byte[]> vs); void addAllMayTTL(String key, List<byte[]> vs, int ttl); void set(String key, long i, byte[] v); byte[] get(String key, long i); List<byte[]> get(String key, List<Long> is); Long left(String key); Long right(String key); int size(String key); void deleteFast(String key); void delete(String key); boolean isExist(String key); List<byte[]> range(String key, long start, long end); @Override @SuppressWarnings("unchecked") RIterator<RList> iterator(String key); Entry getEntry(RocksIterator iterator); List<byte[]> blpop(String key, int num); List<byte[]> brpop(String key, int num); @Override KeyIterator getKeyIterator(); void ttl(String key, int ttl); void delTtl(String key); int getTtl(String key); void addMayTTL(String key, byte[] v, int ttl); final static String HEAD; final static byte[] HEAD_VALUE_B; final static byte[] HEAD_B; }### Answer:
@Test public void delTtl() throws Exception { String head = "delTtl0"; RList list = db.getList(); int num = 1; try { for (int i = 0; i < num; i++) { list.add(head, ("hello" + i).getBytes()); } list.ttl(head, 1); list.delTtl(head); Thread.sleep(6000); for (int i = 0; i < num; i++) { byte[] bytes = list.get(head, i); Assert.assertEquals(new String(bytes), ("hello" + i)); } } finally { list.delete(head); } }