//ww:run-exit 4
package main;
import encoding.utf8;
fn classify(d: *utf8.decoder) int = {
	match (utf8.next(d)) {
	case let r: rune => return 1;
	case let dn: utf8.done => return 2;
	case let m: utf8.more => return 3;
	case let e: utf8.invalid => return 4;
	};
	return 0;
};
export fn main() int = {
	let s: []u8 = [255u8];
	let d = utf8.decode(s);
	return classify(&d);
};