python输出结果后面带着一个“None”

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执行代码的时候，输出的结果中含有一个“None”

from python1.python10.car import Carclass Battery():    """A simple attempt to model a battery for an electric car."""    def __init__(self, battery_size=60):        """Initialize the batteery's attributes."""        self.battery_size = battery_size    def describe_battery(self):        """Print a statement describing the battery size."""        print("This car has a " + str(self.battery_size) + "-kWh battery.")              def get_range(self):        """Print a statement about the range this battery provides."""        if self.battery_size == 60:            range = 140        elif self.battery_size == 85:            range = 185                    message = "This car can go approximately " + str(range)        message += " miles on a full charge."        print(message)        print(range)            class ElectricCar(Car):    """Models aspects of a car, specific to electric vehicles."""    def __init__(self, manufacturer, model, year):        """        Initialize attributes of the parent class.        Then initialize attributes specific to an electric car.        """        super().__init__(manufacturer, model, year)        self.battery = Battery()my_tesla=ElectricCar('tesla','model s',2016)print(my_tesla.get_descriptive_name())my_range=Battery()print（my_range.get_range()）

结果如下

2016 Tesla Model S2016 Tesla Model SThis car can go approximately 140 miles on a full charge.140None

只要将最后一行代码的print() 去掉即可改成 my_range.get_range() 或者是将函数中的print(range) 改成 return range

是因为python函数使用return返回值，如果不用
return, 而用print输出值，这个函数默认还有一个返回值为None

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