### Question:
RMap extends RCollection { @Override public int size(String key) throws KitDBException { try (CloseLock ignored = checkClose()) { byte[] key_b = getKey(key); Meta metaV = getMeta(key_b); if (metaV == null) { return 0; } return metaV.getSize(); } } protected  RMap(DB db); void put(String key, String mkey, byte[] value); void putTTL(String key, String mkey, byte[] value, int ttl); void put(String key, Map<String, byte[]> map); void putMayTTL(String key, int ttl, Map<String, byte[]> map); void putMayTTL(String key, int ttl, String mkey, byte[] value); Map<String, byte[]> get(String key, String... keys); byte[] get(String key, String mkey); void remove(String key, String... keys); @Override void delete(String key); @Override KeyIterator getKeyIterator(); void deleteFast(String key); @Override RIterator<RMap> iterator(String key); @Override Entry getEntry(RocksIterator iterator); @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); static byte[] HEAD_B; final static byte[] HEAD_KEY_B; }### Answer:
@Test public void size() { }