anchor.diff:  
   emptyMap_ get emptyMap => $package$emptyMap;
   
  -abstract class Missing {
  -}
  -class missing_ implements Missing {
  -    missing_() {}
  -}
  -final missing_ $package$missing = new missing_();
  -
  -missing_ get missing => $package$missing;
  +class Missing {
  +    void _$init$Missing([$dart$core.int $bitmap]) {
  +        if (0 != ($bitmap & 1)) {}
  +    }
  +    Missing.instance() : this.instance$d(1);
  +    Missing.instance$d([$dart$core.int $bitmap]) {
  +        _$init$Missing($bitmap | 1);
  +    }
  +}
  +Missing _$s$Missing$instance;
  +
  +Missing get $package$$new$Missing$instance => _$s$Missing$instance != null ? _$s$Missing$instance : _$s$Missing$instance = new Missing.instance();
  +
  +Missing get $new$Missing$instance => $package$$new$Missing$instance;
   
   $dart$core.Object $package$max([Iterable values]) {
       Iterator it = values.iterator();
  
positive.code:     $dart$core.bool defines([$dart$core.Object key]) => $capture$Map$patch$other.defines(key) || $outer$ceylon$language$Map.defines(key);
      $dart$core.Object get([$dart$core.Object key]) => (() {
          $dart$core.Object result = Map.$_$lookup($capture$Map$patch$other, key);
          if ((!(null == result)) && (result == $package$missing)) {
              return $outer$ceylon$language$Map.get(key);
          } else {
              return result;
  
negative.code:     }
      $dart$core.String toString() => ((("" + _$iterable.toString()) + ".repeat(") + _$times.toString()) + ").iterator()";
  }
  Throwable $package$dart$wrapThrownObject([$dart$core.Object thrown]) => (() {
      $dart$core.bool doElse$0 = true;
      if (thrown is Throwable) {
          Throwable thrown$1;
          thrown$1 = thrown as Throwable;
          doElse$0 = false;
          return thrown$1;
      }
      if (doElse$0) {
          return new Exception(thrown.toString());
      }
  })();
  
  Throwable dart$wrapThrownObject([$dart$core.Object thrown]) => $package$dart$wrapThrownObject(thrown);
  
  class functionIterable$$anonymous$0_$$anonymous$1_ implements Iterator {
      functionIterable$$anonymous$0_ $outer$ceylon$language$functionIterable$$anonymous$0_;
      functionIterable$$anonymous$0_$$anonymous$1_([functionIterable$$anonymous$0_ $outer$ceylon$language$functionIterable$$anonymous$0_]) {
  