orElse method
Returns this option when present, and computes one otherwise.
fallback is not called when this option is present.
final name = const None<String>().orElse(() => const Some<String>('guest'));
Implementation
Option<T> orElse(Option<T> Function() fallback) {
return switch (this) {
Some<T>() => this,
None<T>() => fallback(),
};
}