dek5.py

# Correct decorator for an optional parameter
def print_before4(label='label'):

    def decorator(func):

        @functools.wraps(func)
        def wrapped(*args, **kwargs):
            print(label, args, kwargs)
            return func(*args, **kwargs)

        return wrapped

    if callable(label):  # It's a simple decorator call
        return decorator(label)

    return decorator