anchor.diff:        final root = createRoot<String, String, num>();
         expect(root.hasKeyAndValue, isFalse);
         expect(root.hasChildren, isFalse);
  +      expect(root.parts, isEmpty);
         final types = trie.entries.map((each) => each.runtimeType).toSet();
         expect(types.single, root.runtimeType);
       });
  
positive.code:           map.replaceAll('b', [3, 4, 5]);
            expect(map, hasLength(4));
            expect(collection, [3, 4, 5]);
          });
          test('clear', () {
            final map = ListMultimap.fromIterables(['a', 'b', 'b'], [1, 2, 3]);
            final collection = map['b'];
            map.clear();
            expect(map, isEmpty);
            expect(collection, isEmpty);
          });
          test('clear', () {
            final map = ListMultimap.fromIterables(['a', 'b', 'b'], [1, 2, 3]);
  
negative.code:           expect(map.containsValue(2), isTrue);
            expect(map.containsValue(3), isTrue);
            expect(map.containsValue(4), isFalse);
          });
          test('read', () {
            final map = ListMultimap.fromIterables(['a', 'b', 'b'], [1, 2, 3]);
            expect(map['a'], [1]);
            expect(map['b'], [2, 3]);
          });
          test('write', () {
            final map = ListMultimap.fromIterables(['a', 'b', 'b'], [1, 2, 3]);
            map['a'][0] = 4;
            map['b'][0] = 5;
            map['b'][1] = 6;
            expect(map['a'], [4]);
            expect(map['b'], [5, 6]);
          });
        });
        group('modifiers', () {
  