docstring

[YufengXin]

#70.

@sajith already made the constant flag name change.
Used docstring in a few places

[YufengXin]

black reformatting is different in 3.8 (my Mac) and 3.9 (here)?

[YufengXin]

updated my MacOS to Python3.11

[sajith]

Thanks! I have some suggestions about locations of the docstrings. (This PEP might be useful: https://peps.python.org/pep-0257/.)

Not sure the suggestions will be formatted correctly if you accept them, because I made them with GitHub's interface. You might need to run black again.

Please make sure that you have the current version of black, with pip install --upgrade black. (We should probably pin black at the current major version...)

There probably are other things too that we can do (documenting parameters, following suggestions made by pydocstyle etc) but this is a good change. :-)

[YufengXin]

Thanks. Fixed. I've updated all the tools after Python upgrade yesterday