Added typing annotations to io/__init__ (#4224)
Added typing annotations to io/__init__ (#4224)

* style: Added typing annotations

* Specified types for iter and seek.

Co-authored-by: Vasilis Vryniotis <d748cd3f763058dcf20e5489b9bc2373b78db68c@users.noreply.github.com>
Co-authored-by: Vasilis Vryniotis <e9ee0663849a728bc0d21a0b613cfa07b32d7f20@fb.com>
pytorch/vision,pytorch/vision,pytorch/vision,pytorch/vision,pytorch/vision,pytorch/vision