loadFlags method
Implementation
Future<Map<String, EvaluationResult>?> loadFlags() async {
final prefs = await SharedPreferences.getInstance();
String? jsonString = prefs.getString(key);
if (jsonString == null) return null;
return (jsonDecode(jsonString) as Map<String, dynamic>).map(
(key, value) => MapEntry(key, EvaluationResult.fromJson(value)),
);
}