init method
Implementation
Future<void> init(
Map<String, dynamic>? initialData,
Future<String> Function(String) encrypt,
Future<String> Function(String) decrypt,
) async {
_subject = initialData ?? <String, dynamic>{};
_encrypt = encrypt;
_decrypt = decrypt;
RandomAccessFile file = await _getRandomFile();
return file.lengthSync() == 0 ? flush() : _readFile();
}