// (now inaccessible) corresponding JVPs, but ForwardAccumulator's destructor
  // will release remaining references.
  //
  // This method is not thread-safe (and in general ForwardAccumulator is not
  // thread-safe).
  Status Accumulate(
      const string& op_type, const std::vector<TapeTensor>& input_tensors,
      const std::vector<TapeTensor>& output_tensors,