or method
Returns this option when present, and other otherwise.
other is evaluated before the call. Use orElse when computing it is
expensive or has side effects.
final name = const None<String>().or(const Some<String>('guest'));
Implementation
Option<T> or(Option<T> other) {
return switch (this) {
Some<T>() => this,
None<T>() => other,
};
}