:param timer: an int, one of [None (never), -1, 30, 60, 120]
        :return: nothing

def set_auto_shutoff(self, timer):
        """
        :param timer: an int, one of [None (never), -1, 30, 60, 120]
        :return: nothing
        """
        values = {
            "desired_state": {
                "auto_shutoff": timer
            }
        }
        response = self.api_interface.set_device_state(self, values)
        self._update_state_from_response(response)