python decorators

decorators.py

def once(f):
    def fn(*args, **kwargs):
        if not fn.ran:
            fn.ran = True
            return f(*args, **kwargs)
        print("Not calling again.")
    fn.ran = False

    return fn

@once
def decorated_method(message):
    print(message)

def not_decorated_method(message):
    print(message)

if __name__ == '__main__':
    for msg in ["Message 1!", "Message 2!", "Message 3!"]:
        decorated_method(msg)

    for msg in ["Message 1!", "Message 2!", "Message 3!"]:
        not_decorated_method(msg)