return -1;
  }
  return iter->second.second - iter->second.first;
}

TF_Output TF_OperationInput(TF_Input oper_in) {
  const tensorflow::Edge* edge;
  Status s = oper_in.oper->node.input_edge(oper_in.index, &edge);
  if (!s.ok()) {
    return {nullptr, -1};
  }

  return {ToOperation(edge->src()), edge->src_output()};
}