anchor.diff:    @$dart$core.override
     Iterable map(Callable collecting)
       =>  Iterable.$map(this, collecting);
  +
  +  @$dart$core.override
  +  Iterable flatMap(Callable collecting)
  +    =>  Iterable.$flatMap(this, collecting);
   
     @$dart$core.override
     $dart$core.bool contains([$dart$core.Object element])
  
positive.code:     =>  Iterable.$each(this, step);
  
    @$dart$core.override
    $dart$core.bool contains($dart$core.Object element)
      =>  Iterable.$contains(this, element);
  
    @$dart$core.override
  
negative.code:   @$dart$core.override
    Iterable map(Callable collecting)
      =>  Iterable.$map(this, collecting);
  
    @$dart$core.override
    Iterable flatMap(Callable collecting)
      =>  Iterable.$flatMap(this, collecting);
  
    @$dart$core.override
    Iterable get rest
  