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;

  // Total size the attribute value.

  /// Plugins:
  ///   * Must set `status` to `TF_OK` if `region` was updated.
  ///   * Must set `status` to `TF_NOT_FOUND` if `path` doesn't point to an
  ///     existing file or one of the parent entries in `path` doesn't exist.
  ///   * Must set `status` to `TF_FAILED_PRECONDITION` if `path` points to a
  ///     directory or if it is invalid.
  ///   * Must set `status` to `TF_INVALID_ARGUMENT` if `path` points to an
  ///     empty file.