How to use the ocpp.v16.call_result function in ocpp

def on_boot_notification(**kwargs):  # noqa
        assert kwargs['firmware_version'] == "#1:3.4.0-2990#N:217H;1.0-223"

        return call_result.BootNotificationPayload(
            current_time='2018-05-29T17:37:05.495259',
            interval=350,
            # 'Yolo' is not a valid value for for field status.
            status='Yolo',
        )

def on_boot_notification(charge_point_model, charge_point_vendor, **kwargs):  # noqa
        assert charge_point_vendor == "Alfen BV"
        assert charge_point_model == "ICU Eve Mini"
        assert kwargs['firmware_version'] == "#1:3.4.0-2990#N:217H;1.0-223"

        return call_result.BootNotificationPayload(
            current_time='2018-05-29T17:37:05.495259',
            interval=350,
            status='Accepted',
        )

def on_boot_notitication(self, charge_point_vendor, charge_point_model, **kwargs):
        return call_result.BootNotificationPayload(
	    current_time=datetime.utcnow().isoformat(),
	    interval=10,
	    status=RegistrationStatus.accepted
	)