Python decorators with nested functions

nested_function_decorators.py

def without_params(func):
    """
    Outer function takes target function and returns a wrapped one.
    """
    def _without_params(*args, **kwargs):
        """
        Inner function takes target arguments and makes the call.
        """
        return func("Never gonna run around")

    return _without_params

def with_params(val):
    """
    If you need to take params, it's the same but wrapped in another function.
    This one takes the decorator parameters and returns a doubly wrapped function.
    """
    def _with_params(func):
        def __with_params(*args, **kwargs):
            return func(val)
        return __with_params
    return _with_params

@without_params
def a(text):
    print text

@with_params("and desert you!")
def b(text):
    print text

if __name__ == "__main__":
    a(2, 3)
    b("fizz bang")

Why does it only have to be nested functions? Isn't there any other way of implementing it?