python一个模块储存多个类

Car.py:
class Car():
def init(self,make,model,year):
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0
def get_descriptive_name(self):
long_name = str(self.year)+’’+self.make +’’+self.model
return long_name.title()
def read_odometer(self):
print("This car has "+str(self.odometer_reading)+“miles on it”)

def update_odometer(self,mileage):
    if mileage >= self.odometer_reading:
        self.odometer_reading = mileage
    else:
        print("You cannot roll back an odometer")
def increment_odometer(self,miles):
    self.odometer_reading+=miles

class Battery():
def init(self,battery_size =70):
self.battery_size = battery_size
def describe_battery(self):
print("This car has "+str(self.battery_size)+’-kwh battery’)
def get_range(self):
if self.battery_size == 70:
range = 260
elif self.battery_size == 85:
range = 270
message = “This car can go approximately”+str(range)
message +=“miles on a full charge.”
print(message)
class ElectricCar(Car):
def init(self,make,model,year):
super().init(make,model,year)
self.battery = Battery()

**my_electric_car.py**

from Car import ElectricCar
my_tesla = ElectricCar(‘tesla’,‘model s’,2018)

print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()
my_tesla.battery.get_range()