anchor.diff:      Map tabulate([Callable collecting]) => Iterable.$tabulate(this, collecting);
       Map group([Callable grouping]) => Iterable.$group(this, grouping);
       Map summarize([Callable grouping, Callable accumulating]) => Iterable.$summarize(this, grouping, accumulating);
  +    $dart$core.String toString() => Iterable.$get$string(this);
       $dart$core.bool containsEvery([Iterable elements]) => Category.$containsEvery(this, elements);
       $dart$core.bool containsAny([Iterable elements]) => Category.$containsAny(this, elements);
   }
  
positive.code:     Map get coalescedMap => Map.$get$coalescedMap(this);
      Iterable get distinct => Map.$get$distinct(this);
      $dart$core.bool get empty => Collection.$get$empty(this);
      Iterable get permutations => Collection.$get$permutations(this);
      $dart$core.int get size => Iterable.$get$size(this);
      $dart$core.bool longerThan([$dart$core.int length]) => Iterable.$longerThan(this, length);
  
negative.code:     Map tabulate([Callable collecting]) => Iterable.$tabulate(this, collecting);
      Map group([Callable grouping]) => Iterable.$group(this, grouping);
      Map summarize([Callable grouping, Callable accumulating]) => Iterable.$summarize(this, grouping, accumulating);
      $dart$core.String toString() => Iterable.$get$string(this);
      $dart$core.bool containsEvery([Iterable elements]) => Category.$containsEvery(this, elements);
      $dart$core.bool containsAny([Iterable elements]) => Category.$containsAny(this, elements);
  }
  