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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 refresh_client(self):
 """ Refreshes the FindMyiPhoneService endpoint, This ensures that the location data is up-to-date. """

        req = self.session.post(
            self._fmip_refresh_url,
            params=self.params,
            data=json.dumps(
                {
                    'clientContext': {
                        'fmly': True,
                        'shouldLocate': True,
                        'selectedDevice': 'all',
                    }
                }
            )
        )
        self.response = req.json()

        for device_info in self.response['content']:
            device_id = device_info['id']
            if device_id not in self._devices:
                self._devices[device_id] = AppleDevice(
                    device_info,
                    self.session,
                    self.params,
                    manager=self,
                    sound_url=self._fmip_sound_url,
                    lost_url=self._fmip_lost_url,
                    message_url=self._fmip_message_url,
                )
            else:
                self._devices[device_id].update(device_info)

        if not self._devices:
            raise PyiCloudNoDevicesException()