def palindrome(head):
    return palindrome_rec


def palindrome_rec(head, tail):
    if (head == tail):
        return TRUE
    if (head.data != tail.data):
        return FALSE
    palindrome(head.next, get_previews_node(head, tail))


def get_previews_node(head, tail):
    if (head.next == tail):
        return head
    get_previews_node(head.next, tail)


def palindrome_help(head):
    if (head.next == None):
        return head
    palindrome_help(head.next)