python中函数的默认参数

1、demo

>>> def a(x = 100, y = 200):
    print(x + y)

    
>>> a()               ## 这里x = 100, y = 200是默认参数。
300
>>> a(y = 500, x = 2000)
2500
>>> a(x = 1000, y = 800)
1800