CLN, TYP use string types in generics
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them

> We probably need to use a AST parser to do this checking in the longer term.

Agreed - it's in my backlog to make sense of that and to make a better solution (which could be its own package), will get back to you on it when I make progress > > We probably need to use a AST parser to do this checking in the longer term.
> 
> Agreed - it's in my backlog to make sense of that and to make a better solution (which could be its own package), will get back to you on it when I make progress

I just gave it a go and I think I have something which does the job! Will make a PR tomorrow, we can close this one, thanks for pushing me to do it properly :pray: 