anchor.diff:                  {
                       s = element$1 as String;
                   }
  -                append(String.nativeValue(s));
  +                append($dartString(s));
               }
           }
           return this;
  
positive.code:         }
          $dart$core.String oldString = this.toString();
          clear();
          _$delegate.write(String.instance(String.nativeValue(String.instance(oldString).spanTo($ceylonInteger(index - 1))) + String.nativeValue(String.instance(oldString).spanFrom($ceylonInteger(index + length)))));
          return this;
      }
      StringBuilder deleteInitial([$dart$core.int length]) {
  
negative.code:         if (doElse$0) {{
                  $dart$core.bool doElse$4 = true;
                  {
                      $dart$core.int tmp$5 = $ceylonString(unsignedPart).firstIndexWhere(new dart$Callable(([$dart$core.Object $r]) => $ceylonBoolean(($r as Character).letter)));
                      if (!(null == tmp$5)) {
                          $dart$core.int mag;
                          mag = tmp$5;
                          doElse$4 = false;
                          wholePart = $dartString($ceylonString(unsignedPart).spanTo($ceylonInteger(mag - 1)));
                          rest = $dartString($ceylonString(unsignedPart).spanFrom($ceylonInteger(mag)));
                      }
                  }
                  if (doElse$4) {
  