trying pure python cython style

[julesghub]

A little example of "pure python" style in cython. @lmoresi what do you think?

This will make the cython code easier to read. It can also reduce the pain between python and cython, helpful for dev/debugging.

[julesghub]

Further details of pure python
https://cython.readthedocs.io/en/stable/src/tutorial/pure.html#pure-python-mode

[lmoresi]

I think we should adopt this approach. Did we stop because we need to rename the cython module in uw3 ?