anchor.diff:          } else if (longerThan(Integer.nativeValue(to) + 1)) {
               $dart$core.Object last;
               {
  -                $dart$core.Object tmp$13 = this.getFromFirst(Integer.nativeValue(to));
  -                if (null == tmp$13) {
  +                $dart$core.Object tmp$11 = this.getFromFirst(Integer.nativeValue(to));
  +                if (null == tmp$11) {
                       throw new AssertionError("Violated: exists last = this[to]");
                   }
  -                last = tmp$13;
  +                last = tmp$11;
               }
               return $package$span(first, last);
           } else {
  
positive.code:     Iterable get cycled => Iterable.$get$cycled(this);
      Iterable interpose([$dart$core.Object element, $dart$core.Object step = $package$dart$default]) => Iterable.$interpose(this, element, step);
      Iterable get distinct => Iterable.$get$distinct(this);
      Map group([Callable grouping]) => Iterable.$group(this, grouping);
      $dart$core.bool containsEvery([Iterable elements]) => Category.$containsEvery(this, elements);
      $dart$core.bool containsAny([Iterable elements]) => Category.$containsAny(this, elements);
      $dart$core.bool definesEvery([Iterable keys]) => Correspondence.$definesEvery(this, keys);
      $dart$core.bool definesAny([Iterable keys]) => Correspondence.$definesAny(this, keys);
      Iterable getAll([Iterable keys]) => Correspondence.$getAll(this, keys);
  }
  class List$Indexes$$anonymous$1_ implements Iterator {
      List$Indexes $outer$ceylon$language$List$Indexes;
      List$Indexes$$anonymous$1_([List$Indexes $outer$ceylon$language$List$Indexes]) {
          this.$outer$ceylon$language$List$Indexes = $outer$ceylon$language$List$Indexes;
          _$i = 0;
      }
      $dart$core.int _$i;
      $dart$core.Object next() => (($dart$core.Object $lhs$) => null == $lhs$ ? $package$finished : $lhs$)(_$i < $outer$ceylon$language$List$Indexes.size ? (() {
          $dart$core.Object tmp$84 = Integer.instance(_$i);
          Integer.instance(_$i = Integer.nativeValue(Integer.instance(_$i).successor));
          return tmp$84;
      })() : null);
      $dart$core.String toString() => ("" + $outer$ceylon$language$List$Indexes.toString()) + ".iterator()";
  }
  
negative.code:     Iterable get cycled => Iterable.$get$cycled(this);
      Iterable interpose([$dart$core.Object element, $dart$core.Object step = $package$dart$default]) => Iterable.$interpose(this, element, step);
      Iterable get distinct => Iterable.$get$distinct(this);
      Map frequencies() => Iterable.$frequencies(this);
      Map tabulate([Callable collecting]) => Iterable.$tabulate(this, collecting);
      Map group([Callable grouping]) => Iterable.$group(this, grouping);
      Map summarize([Callable grouping, Callable accumulating]) => Iterable.$summarize(this, grouping, accumulating);
      $dart$core.bool containsEvery([Iterable elements]) => Category.$containsEvery(this, elements);
      $dart$core.bool containsAny([Iterable elements]) => Category.$containsAny(this, elements);
  }
  class Iterable$chain$$anonymous$26_ implements Iterable {
      Iterable $outer$ceylon$language$Iterable;
      Iterable $capture$Iterable$chain$other;
      Iterable$chain$$anonymous$26_([Iterable $outer$ceylon$language$Iterable, Iterable $capture$Iterable$chain$other]) {
          this.$outer$ceylon$language$Iterable = $outer$ceylon$language$Iterable;
          this.$capture$Iterable$chain$other = $capture$Iterable$chain$other;
      }
  