### Question:
ZSet extends RCollection { @Override public KeyIterator getKeyIterator() throws KitDBException { try (CloseLock ignored = checkClose()) { return getKeyIterator(HEAD_B); } } protected  ZSet(DB db); void add(String key, byte[] v, long score); void add(String key, List<Entry> entryList); void addMayTTL(String key, int ttl, byte[] v, long score); boolean contains(String key, byte[] value); List<Entry> range(String key, long start, long end, int limit); List<Entry> rangeDel(String key, long start, long end, int limit); @Override @SuppressWarnings("unchecked") RIterator<ZSet> iterator(String key); void remove(String key, byte[]... vs); List<Long> score(String key, byte[]... vs); Long score(String key, byte[] v); @Override void delete(String key); @Override KeyIterator getKeyIterator(); void deleteFast(String key); @Override int getTtl(String key); @Override void delTtl(String key); @Override void ttl(String key, int ttl); @Override boolean isExist(String key); @Override int size(String key); @Override Entry getEntry(RocksIterator iterator); static String HEAD; static byte[] HEAD_B; static byte[] HEAD_SCORE_B; static byte[] HEAD_V_B; }### Answer:
@Test public void getKeyIterator() { }