var fail = true;

int sheep() {
  if (fail) {
    fail = false;
    throw Exception("boom!");
  }

  return 1;
}

Future<dynamic> retry(Function f, {Duration retryDelay, int numberOfRetries}) {
  try {
    return Future.value(f.call());
  } catch (_) {
    if (numberOfRetries > 0) {
      return Future.delayed(
          retryDelay, () => retry(f, numberOfRetries: numberOfRetries - 1));
    } else {
      rethrow;
    }
  }
}

void main() async {
  print(await retry(() => sheep(),
      retryDelay: Duration(seconds: 1), numberOfRetries: 1));
}