Improve flake8-bugbear

[donBarbos]

While working on this PR I noticed that the return type for ast.NodeVisitor.generic_visit is defined as Any, although it always seems to be None. Maybe I'm missing something?

• typeshed/stdlib/ast.pyi:
  

  typeshed/stdlib/ast.pyi

  Line 1897 in f65bdc1

  def generic_visit(self, node: AST) -> Any: ...

• cpython/Lib/ast.py:
  https://github.com/python/cpython/blob/102f825c5112cbe6985edc0971822b07bd778135/Lib/ast.py#L514-L522

[github-actions]

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

[srittau]

While working on this PR I noticed that the return type for ast.NodeVisitor.generic_visit is defined as Any, although it always seems to be None.

I think this is because – like visit – generic_visit can be overwritten by subclasses (even if that's not explicitly documented). And in that case – like visit et al. – it could return an arbitrary value, which is in return returned by visit.

This example also shows why we now require all instances of Any to be documented, so a PR adding a comment would definitely be welcome.