from abc import *


class Car(ABC):
    @abstractmethod
    def start_engine(self):
        pass

    @abstractmethod
    def stop_engine(self):
        pass


class SportCar(Car):
    def __init__(self):
        self.started = False

    def start_engine(self):
        if self.started:
            return False
        print("start engine")
        self.started = True
        return True

    def stop_engine(self):
        print("stop engine")
        self.started = False


car = SportCar()
car.start_engine()