question: self.local_rank in LightningDataModule
context: Hi, I was recently reading this example from NVIDIA DALI:
  https://github.com/NVIDIA/DALI/blob/629c57592b9b4e91b8213e6c77c1af179f7dd079/docs/examples/frameworks/pytorch/pytorch-lightning.ipynb
  I wanted to split the model and datamodule apart. In that case, how can I get local_rank, global_rank and world_size for datamodule's setup?
answer: hey @austinmw !
  you can access them using self.trainer.local_rank, self.trainer.global_rank & self.trainer.world_size.