Example decorators in Python.

decorators.py

def logger(func):
    def wrapped(*args, **kwargs):
        print('Calling {} with args = {} and kwargs = {}'.format(func, args, kwargs))
        return func(*args, **kwargs)
    return wrapped

@logger
def factorial(n):
    if n == 1:
        return 1
    else:
        return n * factorial(n - 1)

@logger
def fibonacci(n):
    if n < 2:
        return n
    else:
        return fibonacci(n - 1) + fibonacci(n - 2)

print(fibonacci(5))
print(factorial(5))