add typehints

[jf---]

as it says on the tin -- I think typehints would be a welcome addition.
@trelau would you accept such a PR, since that would basically make the project python>=3.6+?

[trelau]

Yes, I think so. AFEM depends on pyOCCT which is only supported for 3.6 and above.

As a side note, I've been trying to migrate pyOCCT and pySMESH to latest versions (OCCT 7.5.0 and SMESH 9.6.0) but hit a snag here trelau/SMESH#37. Note I also broke out pySMESH from pyOCCT.

[jf---]

Great to see the 7.5 update is nearby... The smesh breakout is a solid idea...
Great, I'll horse around wrt type hints...

I understand that the issue wrt SMESH is mostly osx related?

[trelau]

Yes it seems osx related and so far has me stumped (and i don't have a local osx system to quickly debug...)

[jf---]

Understood. Is this keeping you from releasing the breakout version of (pay)smesh & pyocct (occt 7.5)?

[trelau]

Yes. I’d like to get pyocct, smesh, and pysmesh fully updated to latest versions of OCCT (7.5) and Salome (9.6) and update the conda feedstock for SMESH. Then refresh afem with new libraries.