def world_db(self, compressors=None):
        """
        Opens a leveldb and keeps it open until editing finished.
        :param compressors: None or tuple of ints: The compressor type(s) to be used.
                If None, the value is decided according to the 'dat_world_version'.
        :yield: DB
        """
        if not self.compressors:
            self.compressors = compressors
        if PocketLeveldbDatabase.holdDatabaseOpen:
            if self._world_db is None:
                self._world_db = self.__open_db()
            yield self._world_db
            pass
        else:
            db = self.__open_db()
            yield db
            del db

        Opens a leveldb and keeps it open until editing finished.
        :param compressors: None or tuple of ints: The compressor type(s) to be used.
                If None, the value is decided according to the 'dat_world_version'.
        :yield: DB
        
pymclevel/leveldbpocket.py