1 #装饰器
 2 def outer(func):
 3     def inner(*args, **kwargs):
 4         print("123")
 5         ret = func(*args, **kwargs)
 6         print("456")
 7         return ret
 8     return inner
 9 @outer
10 def fi(a1, a2):
11     print("F1")
12     return a1 + a2