protected virtual ILiteSetMultimap <ISubKeyMask <TSubKey>, TKey> CreateLiteSetMultimap <TSubKey, TKey>(
     IEqualityComparer <TSubKey> subKeyComparer, IEqualityComparer <TKey> fullKeyComparer)
     where TKey : class, IEnumerable <TSubKey>
 {
     //return CreateSupportDictionary<ISubKeyMask<TSubKey>, ISet<TKey>>(subKeyComparer.ToSubKeyMaskComparer())
     //    .ToSetMultimap(fullKeyComparer);
     return(CreateSupportDictionary <ISubKeyMask <TSubKey>, ISet <TKey> >(subKeyComparer.ToSubKeyMaskComparer())
            .ToSetMultimap(EqualityComparerExtensions.ReferenceEqualityComparerOf <TKey>()));
 }