def log(func):
     def wrapper():
         print("开始执行")
         func()
         print("执行完毕")
     return wrapper


def log_in(func):
    def wrapper():
        print("开始进入...")
        func()
        print("结束...")

    return wrapper

@log
@log_in
def hello():
    print('hello world')

if __name__ == '__main__':
    hello()