// *** in version 6.0: ***
//the attribute marks a conformance
//where both the type and the protocol
//come from another module
extension URL: @retroactive Comparable {
    public static func < (a: URL, b: URL)
        -> Bool {
        a.absoluteString < b.absoluteString
    }
}

let urls = [
    URL(string: "https://b.example")!,
    URL(string: "https://a.example")!]

print(urls.min()!.absoluteString)
//https://a.example