python函数中变量LEGB原则

L-----local 局部名字空间
E-----enclosing 直接外围空间
G-----global 全局名字空间
B-----builtin 内建名字空间
变量名是按照这个顺序搜索的。
看下面这段程序：

x = 99
print("outside of function","x=",x)
def funa(y):
    print("in the funa,x=",x)
    print("in the funa,y=",y)  
    def funb():
        print("in the funb,x =",x)
        print("in the funb,y =",y)
    z=x+y
    funb()
    return z

print(funa(1))
print("outside of function","x=",x)

输出的结果为：

outside of function x= 99
in the funa,x= 99
in the funa,y= 1
in the funb,x = 99
in the funb,y = 1
100
outside of function x= 99