TF_Status* status);

  /// Returns the current write position in `*file`.
  ///
  /// Plugins should ensure that the implementation is idempotent, 2 identical
  /// calls result in the same answer.
  ///
  /// Plugins:
  ///   * Must set `status` to `TF_OK` and return current position if no error.
  ///   * Must set `status` to any other value and return -1 in case of error.