OOP 7: Adding Parameters

Hi dear community. The task https://py.checkio.org/en/mission/oop-series-7-2/ is explained very poorly. That one made me spend time with reading the unit test (https://github.com/CheckiO-Missions/checkio-mission-oop-series-7/blob/master/verification/tests.py) to understand the popped up errors. No surprisingly the task has a negative rating. Thanks to the unit test itself. It helped me to pass the task. But I kindly ask you to formulate tasks better. Thank you.