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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 setup_schedule(self):
        "Called when schedule is intialized. Fetch schedules from DB etc here"

        log.info("SQLAlchemyScheduler.setup_schedule called")

        if 'celery.backend_cleanup' not in self._schedule:
            self._schedule['celery.backend_cleanup'] = ScheduleEntry(
                name='celery.backend_cleanup',
                task='celery.backend_cleanup',
                schedule=crontab('0', '4', '*'),
                options= {'expires': 12 * 3600}
            )