Explain the concept of decorators in Python and how they are used to modify the behavior of functions.

Decorators in Python are functions that take another function and return a new function with modified or extended behavior, without changing the original code of the decorated function.

They are often used for:

• Logging calls
• Access rights checks
• Caching results
• Measuring execution time

Here's an example of a simple decorator that prints a message before and after calling a function:

def decorator(func):
    def wrapper(*args, **kwargs):
        print("Before calling the function")
        result = func(*args, **kwargs)
        print("After calling the function")
        return result
    return wrapper

@decorator
def say_hello(name):
    print(f"Hello, {name}!")

say_hello("World")

The output will be:

Before calling the function
Hello, World!
After calling the function

Thus, decorators allow dynamically changing the behavior of functions without modifying their source code.