swap method

Implementation

@pragma('vm:prefer-inline')
Async<Sync<T>> swap() {
  switch (value) {
    case Ok(value: final asyncValue):
      return Async(() async {
        final innerResult = await asyncValue.value;
        return Sync.result(innerResult);
      });
    case final Err<Async<T>> err:
      final failedSync = Sync.err(err.transfErr<T>());
      return Async.okValue(failedSync);
  }
}