Yes, no problem. The only thing was that I did not really see the need for being able to provide `None`. And while looking at the code, I was thinking it would simplify the code if `None` was not supported.

But actually, for me it doesn't matter (I wouldn't use the None). The only thing is that the other paramaters also don't use ``None``. So for consistency, it is not really necessary to provide the `None` option.