*   Include unit tests when you contribute new features, as they help to a)
    prove that your code works correctly, and b) guard against future breaking
    changes to lower the maintenance cost.
*   Bug fixes also generally require unit tests, because the presence of bugs
    usually indicates insufficient test coverage.
*   Keep API compatibility in mind when you change code in core TensorFlow,
    e.g., code in

  BlockMap block_map_ ABSL_GUARDED_BY(mu_);

  /// The LRU list of block keys. The front of the list identifies the most
  /// recently accessed block.
  std::list<Key> lru_list_ ABSL_GUARDED_BY(mu_);

  /// The LRA (least recently added) list of block keys. The front of the list
  /// identifies the most recently added block.
  ///
  /// Note: blocks are added to lra_list_ only after they have successfully been

  // with the corresponding name prefix or if there is exactly one matching
  // object and it is the directory marker. Therefore we need to retrieve
  // at most two children for the prefix to detect if a directory is empty.
  auto gcs_file = static_cast<GCSFile*>(filesystem->plugin_filesystem);
  auto childrens = GetChildrenBounded(gcs_file, path, 2, true, true, status);