Interesting, Black docs specifically calls out an option for users with that exact use case for mixing single and double-quoted strings (although they do recommend dispensing of it eventually): https://black.readthedocs.io/en/stable/the_black_code_style/...

> If you are adopting Black in a large project with pre-existing string conventions (like the popular “single quotes for data, double quotes for human-readable strings”), you can pass --skip-string-normalization on the command line. This is meant as an adoption helper, avoid using this for new projects.