anchor.diff:  
   abstract class Integral implements Number, Enumerable {
       $dart$core.Object remainder([$dart$core.Object other]);
  -    $dart$core.bool zero;
  -    $dart$core.bool unit;
  +    $dart$core.bool get zero;
  +    $dart$core.bool get unit;
       $dart$core.bool divides([$dart$core.Object other]);
       static $dart$core.bool $divides([final Integral $this, $dart$core.Object other]) => ((other as Integral).remainder($this) as Integral).zero;
   }
   abstract class Invertible implements Summable {
  -    $dart$core.Object negated;
  +    $dart$core.Object get negated;
       $dart$core.Object minus([$dart$core.Object other]);
       static $dart$core.Object $minus([final Invertible $this, $dart$core.Object other]) => $this.plus((other as Invertible).negated);
   }
  
positive.code: Callable or([Callable p, Callable q]) => $package$or(p, q);
  
  abstract class Ordinal {
      $dart$core.Object successor;
      $dart$core.Object predecessor;
  }
  Tuple $package$findPair([Callable selecting, Iterable firstIterable, Iterable secondIterable]) {
      Iterator firstIter = firstIterable.iterator();
  
negative.code:     static Empty $get$reversed([final Empty $this]) => $this;
      Empty sequence();
      static Empty $sequence([final Empty $this]) => $this;
      $dart$core.String toString();
      static $dart$core.String $get$string([final Empty $this]) => "[]";
      $dart$core.Object get lastIndex;
      static $dart$core.Object $get$lastIndex([final Empty $this]) => null;
  