parse static method
Implementation
static HackerNewsUserUrl? parse(String url) {
var matches = RegExp(
r'(?:https?:)?\/\/news\.ycombinator\.com\/user\?id=(?<user>[A-z0-9_-]+)')
.allMatches(url);
var id = matches.getValue("user");
if (id == null) return null;
return HackerNewsUserUrl._(id);
}