pytorch

4bcedb66 - Mark sampler and batch_sampler arguments as optional in the DataLoader interface (#27821)

Mark sampler and batch_sampler arguments as optional in the DataLoader interface (#27821) Summary: Changelog: - DataLoader argument `sampler` is now of type `Optional[Sampler[int]]`instead of `Sampler[int]` - DataLoader argument `batch_sampler` is now of type `Optional[Sampler[Sequence[int]]]` instead of `Sampler[Sequence[int]]` Fixes https://github.com/pytorch/pytorch/issues/27737 Pull Request resolved: https://github.com/pytorch/pytorch/pull/27821 Differential Revision: D17906623 Pulled By: ezyang fbshipit-source-id: 088cacbb7e9f7988995f40b71adc3e719815f5ad