init method
Implementation
Future<void> init(
Map<String, dynamic>? initialData,
Future<String> Function(String) encrypt,
Future<String> Function(String) decrypt,
) async {
_encrypt = encrypt;
_decrypt = decrypt;
_subject.value = initialData ?? <String, dynamic>{};
if (await _exists()) return await _readFromStorage();
return await _writeToStorage(_subject.value);
}