code: def kth_to_last_eval(head, k):
      
      if not isinstance(k, int) or not head.val:
          return False
  
      nexts = '.'.join(['next' for n in range(1, k+1)])
      seeker = str('.'.join(['head', nexts]))
  
      while head:
          if eval(seeker) is None:
              return head
          else:
              head = head.next
  
      return False
docs: This is a suboptimal, hacky method using eval(), which is not
       safe for user input. We guard against danger by ensuring k in an int