anchor.diff:  
     static void run() {
       group('ListBase', (){
  -      test('filter', _testFilter);
  -      test('forEach', _testForEach);
         test('indexOf', _testIndexOf);
  -      test('map', _testMap);
  -      test('reduce', _testReduce);
         test('simple', _testSimple);
         test('last', _testLast);
       });
  
positive.code:     expect(instance.last, 1);
    }
  
    static void _testReduce() {
      expect(instance.reduce(0, (prev, element) => prev + element), 15);
      expect(instance.reduce(1, (prev, element) => prev * element), 120);
    }
  
    static void _testSimple() {
      expect(instance.length, equals(_length));
      expect(instance, orderedEquals([5,4,3,2,1]));
    }
  
    static void _testMap() {
      Func1<int, int> dub = (i) => i * 2;
  
      var list = instance.map(dub);
      expect(list.length, equals(_length));
      expect(list, orderedEquals([10, 8, 6, 4, 2]));
    }
  
    static void _testIndexOf() {
  
negative.code:     expect(flipped.indexOf(0), equals(-1));
      expect(flipped.lastIndexOf(0), equals(-1));
    }
  }
  