anchor.diff:      $dart$core.Object get successor;
       static $dart$core.Object $get$successor([final Enumerable $this]) => $this.neighbour(1);
       $dart$core.Object get predecessor;
  -    static $dart$core.Object $get$predecessor([final Enumerable $this]) => $this.neighbour(Integer.nativeValue(-Integer.instance(1)));
  +    static $dart$core.Object $get$predecessor([final Enumerable $this]) => $this.neighbour(-1);
       $dart$core.int offset([$dart$core.Object other]);
       $dart$core.int offsetSign([$dart$core.Object other]);
       static $dart$core.int $offsetSign([final Enumerable $this, $dart$core.Object other]) => Integer.instance($this.offset(other)).sign;
  
positive.code:         this.$outer$ceylon$language$List$Patch = $outer$ceylon$language$List$Patch;
          this.$capture$$iter = $capture$$iter;
          this.$capture$$patchIter = $capture$$patchIter;
          _$index = Integer.nativeValue(-Integer.instance(1));
      }
      $dart$core.int _$index;
      $dart$core.Object next() {
  
negative.code:                 {
                      $dart$core.bool doElse$136 = true;
                      {
                          GroupEntry tmp$137 = _$store.getFromFirst(index) as GroupEntry;
                          if (!(null == tmp$137)) {
                              GroupEntry entries;
                              entries = tmp$137;
  