[Feature] Add type hints and mypy support

[qequ]

Updated package so it's mypy compatible

Fixes #296

[skorokithakis]

Hello, thanks for this! Did you use Black on the code? If so, could you please add it to CI?

[qequ]

@skorokithakis I've added a CI job for check black linting 👍

[skorokithakis]

This looks good, thank you! To speed up the review, is there any way you could make your changes to schema.py and not run Black on it? Then I can review only your changes, and I'll run Black and push to your PR, and then merge.

[qequ]

@skorokithakis tough I ran Black there are no significant changes made on the code by Black. At most there are three or four methods/functions signatures formatted to multiple lines, but most of the code remains unchanged

[skorokithakis]

Oh, all those changes are manual? OK, I will review ASAP, thanks!

[qequ]

@skorokithakis any updates on this?

[skorokithakis]

Sorry, this looks good to me. Which Python versions can run this? I worry that it uses syntax that's a bit too recent...

[qequ]

@skorokithakis I have made some updates and tested it up to python3.6 and works normally

[skorokithakis]

When you say "up to", what do you mean? 2.7 to 3.6? Surely it can't be 2.7-compatible any more.

[qequ]

@skorokithakis I've tested from 3.6 to 3.10 and works fine. 3.5 and backwards versions doesn't support types

[skorokithakis]

In that case, that's fine, but the setup.py classifiers/etc needs to be changed to the proper supported versions.

[qequ]

@skorokithakis updated classifiers

[skorokithakis]

Looks good, thanks!