code: def test_visible_devices(self):
      num_gpus_before = self.run_process_and_get_exit_code(
          'python -c "import os; import torch; '
          + "os.environ['CUDA_VISIBLE_DEVICES'] = ''; exit(torch.cuda.device_count())\""
      )
      num_gpus_after = self.run_process_and_get_exit_code(
          'python -c "import os; import monai; import torch; '
          + "os.environ['CUDA_VISIBLE_DEVICES'] = ''; exit(torch.cuda.device_count())\""
      )
      self.assertEqual(num_gpus_before, num_gpus_after)
  
file_path: MONAI/tests/test_set_visible_devices.py
imports: from __future__ import annotations
  import os
  import unittest
  from tests.utils import skip_if_no_cuda
label_desc: Use image node_id 2 for calling the TestVisibleDevices obj's underlying member method code with example usage: obj.test_visible_devices() without return types