python中LEGB原则

1、

>>> def a():
    x = 200
    def b():
        print("inner:",x)
    return b()

>>> a()
inner: 200

2、

>>> def a():
    x =  100
    def b():
        x = 300
        print("inner:",x)
    return b()

>>> a()
inner: 300

3、

>>> x = 300
>>> def a():
    def b():
        print("inner:",x)
    return b()

>>> a()
inner: 300

4、

>>> x = 300
>>> def a():
    x = 500
    def b():
        print("inner:",x)
    return b()

>>> a()
inner: 500

5、

>>> x = 300
>>> def a():
    x = 500
    def b():
        x = 700
        print("inner:",x)
    return b()

>>> a()
inner: 700