firstWhereOrNone method
Implementation
Option<T> firstWhereOrNone(bool Function(T element) test) {
  for (final element in this) {
    if (test(element)) return Some(element);
  }
  return const None();
}Option<T> firstWhereOrNone(bool Function(T element) test) {
  for (final element in this) {
    if (test(element)) return Some(element);
  }
  return const None();
}