public static DataSourceStandard <NullableCollectionNullableDataContainerFactory <NullableDefaultedNullableCollectionStateValidator <TValue>, TValue, TValue>, Option <Option <TValue>[]>, Option <TValue>[], ItemCountValidator <Option <TValue> > > ItemCount <TValue>(this NullableDefaultedNullableCollectionStateValidator <TValue> source, int?minimumItems = null, int?maximumItems = null)
 => source.Add(new ItemCountValidator <Option <TValue> >(minimumItems, maximumItems));
 public static DataSourceStandard <NullableCollectionNullableDataContainerFactory <NullableDefaultedNullableCollectionStateValidator <TValue>, TValue, TValue>, Option <Option <TValue>[]>, Option <TValue>[], CustomValidator <Option <TValue>[]> > Assert <TValue>(this NullableDefaultedNullableCollectionStateValidator <TValue> source, string description, Func <Option <TValue>[], bool> validator)
 => source.Add(new CustomValidator <Option <TValue>[]>(description, validator));
 public static DataSourceStandard <NullableCollectionNullableDataContainerFactory <NullableDefaultedNullableCollectionStateValidator <TValue>, TValue, TValue>, Option <Option <TValue>[]>, Option <TValue>[], UniqueValidator <Option <TValue> > > Unique <TValue>(this NullableDefaultedNullableCollectionStateValidator <TValue> source)
 => source.Add(new UniqueValidator <Option <TValue> >());
 public static DataSourceInverted <NullableCollectionNullableDataContainerFactory <NullableDefaultedNullableCollectionStateValidator <TValue>, TValue, TValue>, Option <Option <TValue>[]>, Option <TValue>[], TValueValidator> Not <TValue, TValueValidator>(this NullableDefaultedNullableCollectionStateValidator <TValue> source, Func <NullableDefaultedNullableCollectionStateValidator <TValue>, DataSourceStandard <NullableCollectionNullableDataContainerFactory <NullableDefaultedNullableCollectionStateValidator <TValue>, TValue, TValue>, Option <Option <TValue>[]>, Option <TValue>[], TValueValidator> > validatorFactory)
     where TValueValidator : struct, IValueValidator <Option <TValue>[]>
 => validatorFactory.Invoke(source).InvertOne();