[EASY] Adding virtual to the isUnionType op (#69554)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/69554
Test Plan: Imported from OSS
Reviewed By: mikaylagawarecki
Differential Revision: D33750966
Pulled By: Gamrix
fbshipit-source-id: d2da8138c72709e6d1359df638ac29ca9d0f1556
(cherry picked from commit 00f434ee04ca458941b240732c10d006efce69cc)
