anchor.diff:    }
   
     // setRange.
  -  list.setRange(0, 4, [3, 2, 1, 0]);
  +  list.setRange(0, 4, <int>[3, 2, 1, 0]);
     Expect.listEquals([3, 2, 1, 0], list);
   
     list.setRange(1, 4, list);
  
positive.code:   Expect.throws(() => new List<int?>.filled(0, null).add(4));
    Expect.throws(() => new List.filled(-2, null)); // Not negative. //# 01: ok
    // Not null.
    Expect.throws(() => new List.filled(null, null));
    Expect.listEquals([4], <int>[]..add(4));
    // Is fixed-length.
    Expect.throws(() => new List.filled(0, 42).add(4));
  
negative.code:   Expect.listEquals([9, 9, 9, 9], list);
  
    // sort.
    list.setRange(0, 4, <int>[3, 2, 1, 0]);
    list.sort();
    Expect.listEquals([0, 1, 2, 3], list);
    list.setRange(0, 4, <int>[1, 2, 3, 0]);
    list.sort();
    Expect.listEquals([0, 1, 2, 3], list);
    list.setRange(0, 4, <int>[1, 3, 0, 2]);
    list.sort((a, b) => b! - a!); // reverse compare.
    Expect.listEquals([3, 2, 1, 0], list);
    list.setRange(0, 4, <int>[1, 2, 3, 0]);
    list.sort((a, b) => b! - a!);
    Expect.listEquals([3, 2, 1, 0], list);
  
    // Some Iterable methods.
  
    list.setRange(0, 4, <int>[0, 1, 2, 3]);
    // map.
    testMap(val) {
      return val * 2 + 10;
  