add black formatter to pre-commit

[MarcoGorelli]

closes #4109 (!)

[codecov]

Codecov Report

Merging #4163 into master will not change coverage.
The diff coverage is 62.50%.

@@           Coverage Diff           @@
##           master    #4163   +/-   ##
=======================================
  Coverage   88.75%   88.75%           
=======================================
  Files          89       89           
  Lines       14038    14038           
=======================================
  Hits        12460    12460           
  Misses       1578     1578           

Impacted Files	Coverage Δ
pymc3/step_methods/hmc/quadpotential.py	79.56% <0.00%> (ø)
pymc3/model_graph.py	88.40% <71.42%> (ø)

[AlexAndorra]

Awesome, thanks @MarcoGorelli !

[MarcoGorelli]

No worries! At this point the wiki should probably also have a "Python code style" section, seeing as this and pyupgrade are checked during CI...I'll put something together later

[AlexAndorra]

Ah right, good point 👌 Tell me when you've added the new section / updated the existing ones and I'll read it 😉

[MarcoGorelli]

Ah right, good point ok_hand Tell me when you've added the new section / updated the existing ones and I'll read it wink

Sure, here's a first draft https://github.com/pymc-devs/pymc3/wiki/PyMC3-Python-Code-Style

[AlexAndorra]

That's perfect, thanks @MarcoGorelli 👌
Also, I think this means step 3 of the NB style guide can be merged with step 2 now, can't it?

[MarcoGorelli]

That's perfect, thanks @MarcoGorelli ok_hand

Thanks!

Also, I think this means step 3 of the NB style guide can be merged with step 2 now, can't it?

Not yet, no - currently .pre-commit-config.yaml has black, but not yet nbqa-black, there's still some notebooks left to clean up (else CI will always fail 😄 )