函数的嵌套

def func():
    print(1)
    def f1():
        print(2)
    return f1()
func()

不管在什么位置，只要是函数名+（） 就是在调用此函数
函数调用执行后，函数体中开辟的空间就自动销毁

def func():
    a = 1
    def foo():
        b = 2
        print(b)  # 2
        print(a)  # 1
        def f1():
            print(b)  # 2
        return f1()
    return foo()
print(func())

函数互相引用

def func():
    a = 1
    foo()
    print(a)
def foo():
    b = 2
    print(b)
func()

def a():
    a = 1
    c()
    print(c)
def b():
    b = 2
    print(b)
def c():
    c = 3
    print(a)
def run():
    a()
run()

def func():
    a = 1
    def b():
        print(a)
def foo():
    b = 1
    def z():
        print(func)
        print(b)
    ret = z()
    func()
    return ret
def run():
    foo()
print(run())

def func(a):
    return (a)
def foo(e):
    return (e)
def b(c):
    print(c)
    return 10
print(func(5))