checkAtsign method
Implementation
Future<bool> checkAtsign(String? atSign) async {
if (atSign == null) {
return false;
} else if (!atSign.contains('@')) {
atSign = '@' + atSign;
}
var checkPresence =
await AtLookupImpl.findSecondary(atSign, rootDomain, rootPort);
// ignore: unnecessary_null_comparison
return checkPresence != null;
}