anchor.diff:                          Character next;
                           next = next$8 as Character;
                           doElse$7 = false;
  -                        _$peekedWasSeparator = Boolean.nativeValue($outer$ceylon$language$dartStringSplit$$anonymous$2_.$capture$dartStringSplit$splitting.f(next) as Boolean);
  +                        _$peekedWasSeparator = Boolean.nativeValue(($outer$ceylon$language$dartStringSplit$$anonymous$2_.$capture$dartStringSplit$splitting as Callable).f(next) as Boolean);
                       }
                   }
                   if (doElse$7) {
  
positive.code:         return (() {
              $dart$core.bool doElse$11 = true;
              {
                  Sequential tmp$12 = _$elements.collect(new dart$Callable(([$dart$core.Object $r]) => ($r as Entry).item));
                  if (tmp$12 is Sequence) {
                      Sequence permutation;
                      permutation = tmp$12 as Sequence;
  
negative.code:             $dart$core.bool doElse$11 = true;
              if (!(null == current)) {
                  doElse$11 = false;
                  return ($capture$set$choosing as Callable).f(current, element);
              }
              if (doElse$11) {
                  return element;
  