code: def dev():
      """
      Get the device to use for torch.distributed.
      """
      if th.cuda.is_available():
          return th.device(
              f"cuda:{MPI.COMM_WORLD.Get_rank() % GPUS_PER_NODE}"
          )
      return th.device("cpu")
  
file_path: improved-diffusion/improved_diffusion/dist_util.py
imports: import io
  import os
  import socket
  import blobfile
  from mpi4py import MPI
  import torch
  import torch.distributed
label_desc: Use image node_id 2 for calling a global function with example usage: dev() and returns: th, th