serialize method
Implementation
String serialize(Map<String, dynamic> library, dynamic element, Object3dMeta? meta) {
  if (library[element.uuid] == null) {
    library[element.uuid] = element.toJson(meta: meta);
  }
  return element.uuid;
}String serialize(Map<String, dynamic> library, dynamic element, Object3dMeta? meta) {
  if (library[element.uuid] == null) {
    library[element.uuid] = element.toJson(meta: meta);
  }
  return element.uuid;
}