pytorch

a51b9a82 - Improve docs around Math/DefaultBackend & add PythonDispatcher class. (#50854)

Improve docs around Math/DefaultBackend & add PythonDispatcher class. (#50854) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50854 Test Plan: Imported from OSS Reviewed By: bhosmer Differential Revision: D26008542 Pulled By: ailzhang fbshipit-source-id: e9c0aa97ac2537ff612f5faf348fcb613da09479