}
  int node = signatures_iter->second;

  auto function_iter = revived_objects_.signature_def_functions.find(node);
  if (function_iter == revived_objects_.signature_def_functions.end()) {
    return errors::Internal(
        "Unable to find SignatureDefFunction associated with key ",
        signature_def_key, " despite key being valid.");
  }

  *function = function_iter->second.get();
  return Status();
}