}
  // StringAttrs are not guaranteed to be NUL terminated, but flexbuffers
  // strings expect NUL terminated strings.
  std::string string_separator_str(string_separator.getValue().data(),
                                   string_separator.getValue().size());
  fbb.String("string_separator", string_separator_str);

  auto axis = mlir::dyn_cast_or_null<IntegerAttr>(attrs.get("axis"));
  if (!axis) {