TF_RET_CHECK(tensor_id.index() == 0)
          << "input port designation not supported";
      // Only assign user of argument the input name if the main graph did not
      // have its _Arg nodes lifted into the functions arguments.
      // Ensure name does not get reused.
      (void)exporter.op_to_name_.GetUniqueName(name);
    }
  }

  // Adds nodes for basic block (function) arguments.