}
  }

  // Process attrs
  string required_attrs_comment;
  string optional_attrs_comment;
  for (int i = 0; i < graph_op_def.attr_size(); ++i) {
    // ApiDef attributes must be in the same order as in OpDef since
    // we initialize ApiDef based on OpDef.
    const auto& attr(graph_op_def.attr(i));
    const auto& api_def_attr(api_def.attr(i));
    CHECK_EQ(attr.name(), api_def_attr.name());