在python中，装饰器可以修改行为：

# defining a decorator

def hello_decorator(func):

# inner1 is a Wrapper function in

# which the argument is called

# inner function can access the outer local

# functions like in this case "func"

def inner1():

print("Hello, this is before function execution")

# calling the actual function now

# inside the wrapper function.

func()

print("This is after function execution")

return inner1

# defining a function, to be called inside wrapper

def function_to_be_used():

print("This is inside the function !!")

# passing 'function_to_be_used' inside the

# decorator to control its behavior

function_to_be_used = hello_decorator(function_to_be_used)

# calling the function

function_to_be_used()