<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def devices(self):
 """ Access the devices :returns: twilio.rest.preview.deployed_devices.fleet.device.DeviceList :rtype: twilio.rest.preview.deployed_devices.fleet.device.DeviceList """

        if self._devices is None:
            self._devices = DeviceList(self._version, fleet_sid=self._solution['sid'], )
        return self._devices