anchor.diff:      })();
       Tuple slice([$dart$core.int index]) => (() {
           if (Integer.instance(index).equals(Integer.instance(firstSeq.size))) {
  -            return new Tuple.$withList([firstSeq, secondSeq], null);
  +            return new Tuple.$withList([firstSeq, secondSeq]);
           } else {
               return Sequence.$slice(this, index);
           }
  
positive.code:     Empty trimTrailing([Callable trimming]);
      static Empty $trimTrailing([final Empty $this, Callable trimming]) => $this;
      Tuple slice([$dart$core.int index]);
      static Tuple $slice([final Empty $this, $dart$core.int index]) => new Tuple.$withList([$this, $this], null);
      void each([Callable step]);
      static void $each([final Empty $this, Callable step]) {}
  }
  
negative.code: 
  $dart$core.Object times([$dart$core.Object x, $dart$core.Object y]) => $package$times(x, y);
  
  Tuple $package$unzip([Iterable tuples]) => new Tuple.$withList([tuples.map(new dart$Callable(([Tuple tuple]) => tuple.first)), tuples.map(new dart$Callable(([Tuple tuple]) => tuple.rest))]);
  
  Tuple unzip([Iterable tuples]) => $package$unzip(tuples);
  
  Tuple $package$unzipPairs([Iterable pairs]) => new Tuple.$withList([pairs.map(new dart$Callable(([Tuple pair]) => pair.get(Integer.instance(0)))), pairs.map(new dart$Callable(([Tuple pair]) => pair.get(Integer.instance(1))))]);
  
  Tuple unzipPairs([Iterable pairs]) => $package$unzipPairs(pairs);
  
  Tuple $package$unzipEntries([Iterable entries]) => new Tuple.$withList([entries.map(new dart$Callable(([$dart$core.Object $r$]) => ($r$ as Entry).key)), entries.map(new dart$Callable(([$dart$core.Object $r$]) => ($r$ as Entry).item))]);
  
  Tuple unzipEntries([Iterable entries]) => $package$unzipEntries(entries);
  
  