anchor.diff:  
   abstract
   class Callable {
  -    $dart$core.Function f;
  -    $dart$core.Function s;
  +    $dart$core.Function get f;
  +    s();
   }
   
   //
  
positive.code: //      Optimize by unwrapping (un)flatten layers when possible.
  
  Callable flatten(Callable tupleFunction) {
      return new dart$FlatFunction(tupleFunction);
  }
  
  Callable unflatten(Callable flatFunction) {
      return new dart$UnflatFunction(flatFunction);
  }
  
  class dart$FlatFunction implements $dart$core.Function, Callable {
  
negative.code:         var initialLength = inArgs.length - 1;
          var outArgs = new $dart$core.List(outSize);
  
          // Copy non-spread args
          if (initialLength > 0) {
            outArgs.setRange(0, initialLength, inArgs);
          }
  
          // Add more from the spread arg
          var outIndex = initialLength;
          var seqIndex = 0;
          while (seqIndex < seq.size) {
            outArgs[outIndex] = seq.getFromFirst(seqIndex);
            outIndex++;
  