Create a new python file: example.py
------------------------------------
def my_decorator(f):
	print("before")
	f()
	print("after")


@my_decorator
def my_function():
	print("hello world")
------------------------------------

If you execute the file example.py you should see some output you shouldn't:
(base) C:\Users\emilio\curso_python>python --version
Python 3.7.3
(base) C:\Users\emilio\curso_python>python ejemplo.py
before
hello world
after