Pythonising some function input arguments

Hi,

I have taken the liberty of simplifying a few functions and make them a bit more pythonic without changing the API, so the signature of the function is helpful.

The next step would be to add this information to the docstrings, so we can auto generate a reference.

P.S.: this is the first Python C-API code that I have seen that I can say it looks beautiful. Thanks for the package!