pycharm实现在子类中添加一个父类没有的属性

class Car():
  """一次模拟汽车的简单尝试"""
  def __init__(self, make, model, year):
    """初始化描述汽车的属性"""
    self.make = make
    self.model = model
    self.year = year
    self.odometer_reading = 0

  def get_description_name(self):
    """返回整洁的描述性信息"""
    long_name = str(self.year) + ' ' + self.make + ' ' + self.model
    return long_name.title()

  def read_odometer(self):
    """打印一条指出汽车里程的消息"""
    print("This car has " + str(self.odometer_reading) + " miles on it.")

  def update_odometer(self, mileage):
    """
    将里程读数设置为指定的值
    禁止将里程表读数往回调
    """
    if mileage >= self.odometer_reading:
      self.odometer_reading = mileage
    else:
      print("You can't roll back an odometer!")

  def increment_odometer(self, miles):
    """将里程表读数增加指定的量"""
    self.odometer_reading += miles


class ElectricCar(Car):
  """电动汽车的独特之处"""
  def _init_(self, make, model, year):
    """
    电动汽车的独特之处
    初始化父类的属性，再初始化电动汽车特有的属性
    """
    super().__init__(make, model, year)
    self.battery_size = 70

  def describe_battery(self):
    """打印一条描述电瓶容量的消息"""
    print("This car has a " + str(self.battery_size) + "-kwh battery.")

my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_description_name())
my_tesla.describe_battery()

Traceback (most recent call last):
 File "E:/Python编程从入门到精通配套资料/Self-taught Python/electric_car.py", line 50, in <module>
  my_tesla.describe_battery()
 File "E:/Python编程从入门到精通配套资料/Self-taught Python/electric_car.py", line 46, in describe_battery
  print("This car has a " + str(self.battery_size) + "-kwh battery.")
AttributeError: 'ElectricCar' object has no attribute 'battery_size'

class Animal():
  def __init__(self, weight, high):
    self.weight = weight
    self.high = high
  def shout(self):
    print('wow')

class Dog(Animal):
  pass

dog_1 = Dog(20,40)
print(dog_1.high)
print(dog_1.weight)
dog_1.shout()
#输出内容是
40
20
wow

class Dog(Animal):
  def run(self):
    print('running')

dog_1 = Dog(20,40)
dog_1.run()
#输出结果是
running

class Cat(Animal):
  def shout(self):
    print('miao')

cat_1 = Cat(20, 40)
cat_1.shout()
#输出结果是
miao

class Cat(Animal):
  def __init__(self, weight, high, color):
    super().__init__(weight, high)
    self.color = color
  def shout(self):
    print('miao')

cat_2 = Cat(20, 40, 'yellow')
print(cat_2.color)
#输出结果是
yellow