Use black as the python code formatter.

[shaoyijia]

1. Set up black code formatter for this repo to ensure code quality. Update README.md and CONTRIBUTING.md accordingly.
2. Reformat knowledge_storm/ using black.

[Yucheng-Jiang]

I'm thinking about following workflow:

• Require each developer to install pre-commit hook to enforce running the code formatter automatically upon every commit. Documentation: https://pre-commit.com.
• Add main branch protection by running "check style" script, to enforce all incoming code is properly formatted.

Rationale for using combination of these two method:

1. Developers do not need to manually run code formatter every time
2. When developers properly configure pre-commit hook, everything will be automatic; when they haven't configure pre-commit hook, the branch protection will reject merge action.
3. There is option to setup CI/CD workflow to auto run code formatter, but it will create code formatting commit upon every push, which I think it's not neat? But not a big concern.

[shaoyijia]

but it will create code formatting commit upon every push

Yes, I also think this is not neat. Previously, I also found an unofficial action that can also reformat the code based on the identified format issue. But I think the change will not be transparent enough to developer and they may fail to test the reformatted code (reformatting the code shall be safe, but just in case).

Require each developer to install pre-commit hook

I can see the benefit, but given this repo mainly hosts a python package, will this "overkill"? Also, I am not sure if everyone is familiar with this.

[shaoyijia]

More thoughts on this @Yucheng-Jiang ?

[Yucheng-Jiang]

For pre-hook, on our end we just need to add .pre-commit-config.yaml. For the developers, they only need to do

pip install pre-commit
pre-commit install

Upon commit, it will run code formatter automatically.

[shaoyijia]

ok, I will look into this. Thanks