anchor.diff: -class Tuple<T1, T2> {
  +class Tuple<T1 extends Hashable, T2 extends Hashable>
  +  implements Hashable {
     final T1 Item1;
     final T2 Item2;
   
  
positive.code:   }
  
    String toString() => "Tuple: Item1: $Item1, Item2: $Item2";
  }
  
  class Tuple3<T1, T2, T3> extends Tuple<T1, T2> {
    final T3 Item3;
  
    const Tuple3(T1 param1, T2 param2, this.Item3) :
  
negative.code:   }
  
    String toString() => "Tuple3: Item1: $Item1, Item2: $Item2, Item3: $Item3";
  
    int hashCode() => Util.getHashCode([Item1, Item2, Item3]);
  }
  