Circular Linked List

Code:

public static class CircularLinkedList
{
    public static LinkedListNode<T> NextOrFirst<T>(this LinkedListNode<T> current)
    {
        return current.Next ?? current.List.First;
    }

    public static LinkedListNode<T> PreviousOrLast<T>(this LinkedListNode<T> current)
    {
        return current.Previous ?? current.List.Last;
    }

    public static LinkedListNode<T> Rewind<T>(this LinkedListNode<T> current, int num)
    {
        while (num != 0)
        {
            current = num > 0 ? current.NextOrFirst() : current.PreviousOrLast();
            num -= Math.Sign(num);
        }
        return current;
    }
}