[typed_subpart_iterator](https://github.com/python/typeshed/blob/60a6695e77b81d0e1b5a088c316af78c7510941f/stdlib/email/iterators.pyi#L8) is defined as returning a `Iterator[str]` but it should be `Iterator[Message]` since it yields `Message` instance [subparts](https://docs.python.org/3/library/email.iterators.html#email.iterators.typed_subpart_iterator).
typed_subpart_iterator is defined as returning a
Iterator[str]but it should beIterator[Message]since it yieldsMessageinstance subparts.