code: def pin_model_to_device(device, model):
      isCUDA = device == "GPU"
      if isCUDA:
          # Bluefog: pin GPU to local rank.
          device_id = (
              bf.local_rank()
              if bf.nccl_built()
              else bf.local_rank() % torch.cuda.device_count()
          )
          torch.cuda.set_device(device_id)
          model.cuda()
      return isCUDA
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import pytest
  import numpy
  import torch
  import torch.nn
  import torch.optim
  from torch.utils.data import Dataset, DataLoader
  import bluefog.torch
  from bluefog.common import topology_util
label_desc: Use image node_id 2 for calling a global function with example usage: pin_model_to_device(device, model) and returns: isCUDA