Simplify boolean return logic

[nickdrozd]

I was poking around in the code and I noticed that there are a lot of bare boolean returns. For example:

        if self.subtype_context.keep_erased_types:
            return False
        return True

This can be simplified to:

        return not self.subtype_context.keep_erased_types

That's a pretty simple case. Other cases are more complicated, but similar in spirit.

This is a refactoring PR that should not change any behavior. By my count it results in a net reduction of 32 return statements.

If this sort of change is welcome, I can keep going.

[hauntsaninja]

Thanks, but several of these make the code less readable. In general, some of these sequences of if conditions are pretty subtle and it's much easier to read them one at a time than to have them compressed into a single statement. I've commented on the ones I think are worthwhile, if you want to pursue this PR, please remove the others :-)

[nickdrozd]

Okay, I think I got all of them.

[nickdrozd]

I fixed the existing changes and added a few more. All the new changes are pretty small, and they can be kept or not.

In the spirit of simplified boolean logic, it would be easier if you mark the ones to reject, rather than the ones to keep 😄

[hauntsaninja]

Thanks, reviewed the new changes. Please don't add any others in this PR :-)

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[hauntsaninja]

Thank you!

[nickdrozd]

Thanks for reviewing!