Linked lists in MIPS - point of example?

Question

I am working with linked lists in MIPS, and have one example that I am not sure about. It says: write function rotate(head, a, b) that rotates elements of linked lists from position a to position b, such that if element was on position i(that belongs segment a,b) its new position is b+a-i. Numbers a,b are choosen such that a<b. Now, I don't get point of this example, because after we change elements for every position i, list will stay the same because of the formula(also it is considered that position of elements in list starts with 1 and goes to length of list).

Also, for every node in list, I think it is enough to replace only value field for corresponding indexes right(next field is not neccessary). Last sentence I am considering only if I had example where elements of list would really change(if my assumption above is correct).