What is a Python decorator and how do you use it?

A Python decorator is a design pattern that allows you to dynamically extend the behavior of a callable object (functions, methods, or classes) without permanently modifying it. In Python, decorators are defined using the ‘@’ symbol followed by the name of the decorator function or class above the definition of the function, method, or class you want to decorate.

Here is a simple example to demonstrate how you can use a Python decorator:

def my_decorator(func):

def wrapper():

print("Something is happening before the function is called.")

func()

print("Something is happening after the function is called.")

return wrapper

@my_decorator

def say_hello():

print("Hello!")

say_hello()

In the above example, the `my_decorator` function is used as a decorator to add behavior before and after the `say_hello` function is called. When `say_hello()` is invoked, it actually calls the `wrapper` function defined inside the decorator function `my_decorator`.

This is a basic example, and decorators can be much more complex and versatile in Python based on the use case and requirements.