id: no-only-defined-names-in-dunder-all
valid:
  - |
    def foo():
        pass
    __all__ = ["foo"]  # string literals - safe
  - |
    class Bar:
        pass
    __all__ = ()  # empty tuple
  - |
    __all__ = []  # empty list
invalid:
  - |
    def foo():
        pass
    __all__ = [foo]  # identifier in list (could be undefined)