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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 _callUpgradeAgent(self, ev_data, failTimeout) -> None: """ Callback which is called when upgrade time come. Writes upgrade record to upgrade log and asks node control service to perform upgrade :param when: upgrade time :param version: version to upgrade to """


        logger.info("{}'s upgrader calling agent for upgrade".format(self))
        self._actionLog.append_started(ev_data)
        self._action_start_callback()
        self.scheduledAction = None
        asyncio.ensure_future(
            self._sendUpgradeRequest(ev_data, failTimeout))