//     * Refer to "TensorFlow Versioning Strategy" section at
//       https://github.com/tensorflow/community/pull/257/files.
//     * Note that the API is still under active development and doesn't have
//       versioning guarantees yet.
//   * `void* ext` is a free-form field that can be populated by
//     a plugin in `TP_*` structs or potential future extension points .
//
// Example usage:
//

// See TF_AddGradientsWithPrefix, which provides a means to specify a custom
// name prefix for operations added to a graph to compute the gradients.
//
// WARNING: This function does not yet support all the gradients that python
// supports. See
// https://www.tensorflow.org/code/tensorflow/cc/gradients/README.md
// for instructions on how to add C++ more gradients.

                         TF_TransactionToken* token, TF_Status* status);

  /// Adds file/directory in the `path` to transaction in `token`. It is a valid
  /// operation to add a path that doesn't exist yet to a transaction.
  ///
  /// In case of error, plugins must set `status` to a value different than
  /// `TF_OK`, free memory allocated for `token` and return -1.
  ///