anchor.diff:      queue.retainAll([1, 3, 5, 7, 9, 10]);  // Remove 2 and 8.
       testLength(17, queue);
   
  -    queue.removeMatching((x) = x == 7);
  +    queue.removeMatching((x) => x == 7);
       testLength(14, queue);
   
  -    queue.retainMatching((x) = x != 3);
  +    queue.retainMatching((x) => x != 3);
       testLength(11, queue);
   
       Expect.listEquals([9, 1, 5, 9, 10, 1, 5, 9, 10, 1, 5], queue.toList());
  
positive.code:     Expect.isTrue(queue.isEmpty);
  
      testAddAll();
      testLarge();
      testFromListToList();
    }
  
negative.code:     }
  
      for (int i = 1; i <= 10; i++) {
        queue.addFirst(11 - i);
        testLength(10 + i, queue);
      }
  
  