getExpiration method

Implementation

Future<Duration?> getExpiration(
) async {
  final request = RequestRepositoryGetExpiration(
    repo: handle,
  );
  final response = await client.invoke(request);
  switch (response) {
    case ResponseDuration(value: final value): return value;
    case ResponseNone(): return null;
    default: throw UnexpectedResponse();
  }
}