Memento

class Memento:
    def __init__(self, counter):
        self.__counter = counter

    def get_state(self):
        return self.__counter

    def set_state(self, counter):
        self.__counter = counter


class Originator:
    def __init__(self, counter=0):
        self.__counter = counter

    def increase(self, value=1):
        self.__counter += value

    def get_counter(self):
        return self.__counter

    def create_memento(self):
        return Memento(self.__counter)

    def set_memento(self, memento: Memento):
        self.__counter = memento.get_state()


class CareTaker:
    def __init__(self, originator: Originator):
        self.originator = originator
        self.mementos = []

    def remember(self):
        self.mementos.append(self.originator.create_memento())

    def go_back(self):
        self.originator.set_memento(self.mementos.pop())

    def wait_day(self):
        self.originator.increase(24)

    def wait_week(self):
        self.originator.increase(168)

    def get_last_memento(self):
        return self.mementos[-1].get_state()


if __name__ == "__main__":
    clock = Originator()
    delivery = CareTaker(clock)

    delivery.remember()
    print("First:", clock.get_counter())

    delivery.wait_day()

    delivery.remember()
    print("Second:", clock.get_counter())

    delivery.wait_week()

    delivery.remember()
    print("Third:", clock.get_counter())

    delivery.go_back()
    print("Go back once:", clock.get_counter())

    delivery.go_back()
    print("Go back twice:", clock.get_counter())

    print("CareTaker get private state of Originator:", delivery.get_last_memento())

    delivery.go_back()
    print("Go back three times:", clock.get_counter())