理解：

 

规律：

一个函数可以被多个装饰器装饰.
@wrapper1
@wrapper2
def target():
    print('我是目标')

规则和规律 wrapper1 wrapper2 TARGET wrapper2 wrapper1

def wrapper1(fn):  # fn: wrapper2.inner
    def inner(*args, **kwargs):
        print("这里是wrapper1 进入")  # 1
        ret = fn(*args, **kwargs)  # wrapper2.inner
        print("这里是wrapper1 出去")  # 5
        return ret
    return inner

def wrapper2(fn):  # fn: target
    def inner(*args, **kwargs):
        print("这里是wrapper2 进入")  # 2
        ret = fn(*args, **kwargs)  # target
        print("这里是wrapper2 出去")  # 4
        return ret
    return inner


@wrapper1  # target = wrapper1(wrapper2.inner)   =>  target: wrapp1.inner
@wrapper2  # target = wrapper2(target)   => target: wrapper2.inner
def target():
    print('我是目标')  # 3

target()

 结果：