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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 service_observable(self, limit) -> int: """ Service the observable's inBox and outBox :return: the number of messages successfully serviced """

        if not self.isReady():
            return 0
        o = self._service_observable_out_box(limit)
        i = await self._observable.serviceQueues(limit)
        return o + i