pytorch

9a03e654 - Adding functional way of stacking DataPipes with fixed mypy (#52885)

Adding functional way of stacking DataPipes with fixed mypy (#52885) Summary: Readding reverted PR with MyPY fixed Pull Request resolved: https://github.com/pytorch/pytorch/pull/52885 Reviewed By: ejguan Differential Revision: D26676405 Pulled By: VitalyFedyunin fbshipit-source-id: 020216c5522d21a4994cd896ae778c0b77f6444b