IPostingList.cs

public interface IPostingList<TEnum>
    where TEnum: struct, IPostingListEnumerator
{
    public ulong FirstValue { get; }
    
    public ulong NumberOfResults { get;  }

    public TEnum Enumerate(ulong start)
}

public interface IPostingListEnumerator
{
    bool MoveNext(out Span<long> range);
}