from abc import ABCMeta, abstractmethod

NOT_IMPLEMENTED = "You should implement this."

class AbstractCar:

    __metaclass__ = ABCMeta

    @abstractmethod

    def drive(self):

        raise NotImplementedError(NOT_IMPLEMENTED)

class Car(AbstractCar):

    def drive(self):

        print("Car has been driven!")

class Driver(object):

    def __init__(self, age):

        self.age = age

class ProxyCar(AbstractCar):

    def __init__(self, driver):

        self.car = Car()

        self.driver = driver

    def drive(self):

        if self.driver.age <= 16:

            print("Sorry, the driver is too young to drive.")

        else:

            self.car.drive()

driver = Driver(16)

car = ProxyCar(driver)

car.drive()

driver = Driver(25)

car = ProxyCar(driver)

car.drive()