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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:
 async def _cleanup(self):
 """ Periodically removes completed tasks from the collection, allowing fire-and-forget tasks to be garbage collected. This does not delete the task object, it merely removes the reference in the scheduler. """

        while True:
            await asyncio.sleep(CLEANUP_INTERVAL_S)
            self._tasks = {t for t in self._tasks if not t.done()}