namespace System.Collections.Generic
{
    public class HashSet<T> : ICollection<T>, IEnumerable, IEnumerable<T>, IReadOnlyCollection<T>, IReadOnlySet<T>, ISet<T>, IDeserializationCallback, ISerializable
    {
        public AlternateLookup<TAlternate> GetAlternateLookup<TAlternate>();
    }
}