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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 _lock_renewer(lockref, interval, stop):
 """ Renew the lock key in redis every `interval` seconds for as long as `self._lock_renewal_thread.should_exit` is False. """

        log = getLogger("%s.lock_refresher" % __name__)
        while not stop.wait(timeout=interval):
            log.debug("Refreshing lock")
            lock = lockref()
            if lock is None:
                log.debug("The lock no longer exists, "
                          "stopping lock refreshing")
                break
            lock.extend(expire=lock._expire)
            del lock
        log.debug("Exit requested, stopping lock refreshing")