isStale method
Whether the model at path is to be cooked and its cooked copy is
missing or was made from another file or other settings.
Implementation
bool isStale(String path) {
if (!hasSettings(path) && !isCooked(path)) return false;
final source = _file(path);
if (!source.existsSync()) return false;
final cooked = _file(ModelImportSettings.cookedOf(path));
if (!cooked.existsSync()) return true;
final stamp = CookedModel.stampOf(readCookedHead(cooked.path));
return stamp != cookStamp(source.readAsBytesSync(), settingsOf(path));
}