typedef struct TF_AttrMetadata {
  // A boolean: 1 if the attribute value is a list, 0 otherwise.
  unsigned char is_list;

  // Length of the list if is_list is true. Undefined otherwise.
  int64_t list_size;

  // Type of elements of the list if is_list != 0.
  // Type of the single value stored in the attribute if is_list == 0.
  TF_AttrType type;

  void (*path_exists)(const TF_Filesystem* filesystem, const char* path,
                      TF_Status* status);

  /// Checks if all values in `paths` exist in the filesystem.
  ///
  /// Returns `true` if and only if calling `path_exists` on each entry in
  /// `paths` would set `status` to `TF_OK`.
  ///
  /// Caller guarantees that:
  ///   * `paths` has exactly `num_files` entries.