add comma to prevent syntax errors (#62492)
Summary:
Fixes #{issue number}
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62492
Reviewed By: VitalyFedyunin
Differential Revision: D30304684
Pulled By: ezyang
fbshipit-source-id: db08ca39bcecbfd79ea50df18536bf4e87f51e15
