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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fail(self) -> None: """ for testing purposes only. always fail in commit """


        _debug("fail")

        # on commit carry out action; on rollback reverse rename
        def on_commit(_obj):
            raise_testfailure("commit")

        def on_rollback(_obj):
            raise_testfailure("rollback")

        return self._process(on_commit, on_rollback)