type Constructor<T = {}> = new (...args: any[]) => T;
//                                                 ^ defined: 1

function Timestamped<TBase extends Constructor>(Base: TBase) {
//                                                    ^ defined: 4
  return class extends Base {
  //                   ^ defined: 4
    timestamp: number;
  };
}

class User {
  name: string;
}

const TimestampedUser = Timestamped(User);
//                      ^ defined: 4
//                                  ^ defined: 12

let tsu = new TimestampedUser();
//            ^ defined: 16

  tsu.name;
//^ defined: 20
//    ^ defined: 13

  tsu.timestamp;
//^ defined: 20
//    ^ defined: 8

export {}