text: # pycharm help的测试用例 https://www.jetbrains.com/help/pycharm/creating-and-running-your-first-python-project.html
  class Car:
  
      def __init__(self, speed=0):
          self.speed = speed
          self.odometer = 0
          self.time = 0
  
      def say_state(self):
          print("I'm going {} kph!".format(self.speed))
  
      def accelerate(self):
          self.speed += 5
  
      def brake(self):
          self.speed -= 5
  
      def step(self):
          self.odometer += self.speed
          self.time += 1
  
      def average_speed(self):
          if self.time != 0:
              return self.odometer / self.time
          else:
              pass
  
  
  if __name__ == '__main__':
  
      my_car = Car()
      print("I'm a car!")
      while True:
          action = input("What should I do? [A]ccelerate, [B]rake, "
                   "show [O]dometer, or show average [S]peed?").upper()
          if action not in "ABOS" or len(action) != 1:
              print("I don't know how to do that")
              continue
          if action == 'A':
              my_car.accelerate()
          elif action == 'B':
              my_car.brake()
          elif action == 'O':
              print("The car has driven {} kilometers".format(my_car.odometer))
          elif action == 'S':
              print("The car's average speed was {} kph".format(my_car.average_speed()))
          my_car.step()
          my_car.say_state()