Write test case where a hook accepts *args or **kwargs

[dzervas]

I think the way that I count the arguments available in a hook is flawed.

In case a single (1) argument is *args, it should accept unlimited arguments. Same with **kwargs for keyword arguments.

Also there is a corner case for usage of *__retvals__ or **__retvals__

I should at least add it to the test cases - I think it won't work as expected (hooker will think that the hook accepts only 1 argument)