code: def test_locking(self):
      with FileLock(self.TEST_DIR / "lock"):
          # Trying to acquire the lock again should fail.
          with pytest.raises(Timeout):
              with FileLock(self.TEST_DIR / "lock", timeout=0.1):
                  pass
  
      # Trying to acquire a lock when lacking write permissions on the file should fail.
      with pytest.raises(PermissionError):
          with FileLock(self.TEST_DIR / "read_only_lock"):
              pass
  
      # But this should only issue a warning if we set the `read_only_ok` flag to `True`.
      with pytest.warns(UserWarning, match="Lacking permissions"):
          with FileLock(
              self.TEST_DIR / "read_only_lock", read_only_ok=True
          ):
              pass
  
      # However this should always fail when we lack write permissions and the file lock
      # doesn't exist yet.
      with pytest.raises(PermissionError):
          with FileLock(
              self.TEST_DIR / "read_only_dir" / "lock",
              read_only_ok=True,
          ):
              pass
  
imports: import os
  import pathlib
  import json
  import time
  import shutil
  from filelock import Timeout
  import pytest
  import responses
  import torch
  from allennlp.common.file_utils import FileLock, _resource_to_filename, filename_to_url, cached_path, open_compressed, CacheFile, _Meta, _find_entries, inspect_cache, remove_cache_entries, LocalCacheResource, TensorCache
  from allennlp.common import Params
  from allennlp.modules.token_embedders import ElmoTokenEmbedder
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.predictors import Predictor
label_desc: Use image node_id 2 for calling the TestFileLock obj's underlying member method code with example usage: obj.test_locking() without return types