importMnemonic function
Implementation
Future<dynamic> importMnemonic(String walletId, String mnemonic) async {
final oldMnemonic = await _storage.read(key: walletId);
if (oldMnemonic != null && oldMnemonic.isNotEmpty) {
return Future.error(ErrorCode.mnemonicAlreadyExists);
}
await _storage.write(key: walletId, value: mnemonic);
}