// Temporarily push or pop transient state for this accumulator.
  //
  // Allows an accumulator which is currently processing an operation to
  // temporarily reset its state. Without pushing and popping, accumulators
  // ignore operations executed as a direct result of their own jvp
  // computations.
  void PushState() { call_state_.emplace(nullptr, false); }
  void PopState() { call_state_.pop(); }

 private:

  /// of them. Ownership of options and buffers therein belongs to the caller
  /// and any buffers need to be allocated through filesystem allocation API.
  /// Filesystems may choose to ignore configuration errors but should at least
  /// display a warning or error message to warn the users.
  ///
  /// Plugins:
  ///   * Must set `status` to `TF_OK` if options are updated.