
    @Override
    public BunchSetId getKeyFromInt(int key) {
        return (key == LangbookDbSchema.EMPTY_BUNCH_SET_ID)? EMPTY : new BunchSetId(key);
    }

    @Override
    public BunchSetId getKeyFromDbValue(DbValue value) {
        return getKeyFromInt(value.toInt());
    }

    @Override
    public BunchSetId getDeclaredEmpty() {
        return EMPTY;