human
Solve in Python:
This kata is about singly 
linked list.  A linked list is an ordered set of data elements, each containing a link to its successor (and sometimes its predecessor, known as a double linked list).  You are you to implement an algorithm to find the kth to last element.

For example given a linked list of:
a -> b -> c -> d

if k is the number one then d should be returned
if k is the number two then c should be returned
if k is the number three then b should be returned
if k is the number four then a should be returned
if k exceeds the size of the list then None returned


Special Note --> Node classes contain two fields.
data and next.
And to access the head of the list, use head. e.g. linked_list.head

Write me a Python program to find the kth to last element?
assistant
#Here is Python program to find the kth to last element.

def search_k_from_end(linked_list, k):
    def rec(node, x):
        if not node: return x
        n = rec(node.next, x)
        return n if type(n) != int else n-1 if n else node
    res = rec(linked_list.head, k-1)
    if type(res) != int: return res.data