def __del_transaction_support(self):
        "Ensures no pending transactions and removes unsaved columns."
        assert not self.__locked.value.where(locked=True), \
            'You must commit all transactions before pickling!'
        self.__data.alter_drop('type')
        self.__data.alter_drop('lock')
        self.__data.alter_drop('copy')
Ensures no pending transactions and removes unsaved columns.
recipes/Python/577825_Rudimentary_Database_Engine/recipe-577825.py