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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 update(self, friendly_name=values.unset, default_deployment_sid=values.unset):
 """ Update the FleetInstance :param unicode friendly_name: A human readable description for this Fleet. :param unicode default_deployment_sid: A default Deployment SID. :returns: Updated FleetInstance :rtype: twilio.rest.preview.deployed_devices.fleet.FleetInstance """

        return self._proxy.update(
            friendly_name=friendly_name,
            default_deployment_sid=default_deployment_sid,
        )