anchor.diff:      $dart$core.bool definesAny([Iterable keys]) => Correspondence.$definesAny(this, keys);
       Iterable getAll([Iterable keys]) => Correspondence.$getAll(this, keys);
   }
  -class GroupEntry {
  +class GroupEntry implements dart$$Basic {
       GroupEntry([GroupEntry next, $dart$core.Object group, $dart$core.Object elements]) {
           this.next = next;
           this.group = group;
  
positive.code: 
  empty_ get empty => $package$empty;
  
  class emptyIterator_ implements Iterator {
      emptyIterator_() {}
      Finished next() => $package$finished;
      $dart$core.String toString() => "empty.iterator()";
  
negative.code:     $dart$core.bool containsEvery([Iterable elements]) => Category.$containsEvery(this, elements);
      $dart$core.bool containsAny([Iterable elements]) => Category.$containsAny(this, elements);
  }
  class Map$mapItems$$anonymous$3_ implements dart$$Object, Map {
      Map $outer$ceylon$language$Map;
      Callable $capture$Map$mapItems$mapping;
      Map$mapItems$$anonymous$3_([Map $outer$ceylon$language$Map, Callable $capture$Map$mapItems$mapping]) {
  