def concat(xs: Optional[ListNode), ys: Optional[ListNode]) -> Optional[ListNode] : Return the head of a linked list that represents the concatenation of the given lists, such that xs comes before ys. >>> xs = ListNode(1, ListNode(2, ListNode(3, None))) >>> ys = ListNode(4, ListNode(5, None)) >>> concat(xs, ys) ListNode(1, ListNode(2, ListNode(3, ListNode(4, ListNode(5, None))))) def sum_list(head: Optional[ListNode]) -> int: Return the sum of all integers in each ListNode in the list. If the list is empty, return 0. >>> head = ListNode(1, ListNode(2, ListNode(3, None))) >>> sum_list(head) 6 def exp_list(head: Optional[ListNode], exp: int) -> Optional[ListNode]: Return the head of a linked list in which the integer in each ListNode has been raised to the exp power. >>> head = ListNode(1, ListNode(2, ListNode(3, None))) >>> exp_list(head, 3) ListNode(1, ListNode(8, ListNode (27, None))) def concat(xs: Optional[ListNode), ys: Optional[ListNode]) -> Optional[ListNode] : Return the head of a linked list that represents the concatenation of the given lists, such that xs comes before ys. >>> xs = ListNode(1, ListNode(2, ListNode(3, None))) >>> ys = ListNode(4, ListNode(5, None)) >>> concat(xs, ys) ListNode(1, ListNode(2, ListNode(3, ListNode(4, ListNode(5, None))))) def sum_list(head: Optional[ListNode]) -> int: Return the sum of all integers in each ListNode in the list. If the list is empty, return 0. >>> head = ListNode(1, ListNode(2, ListNode(3, None))) >>> sum_list(head) 6 def exp_list(head: Optional[ListNode], exp: int) -> Optional[ListNode]: Return the head of a linked list in which the integer in each ListNode has been raised to the exp power. >>> head = ListNode(1, ListNode(2, ListNode(3, None))) >>> exp_list(head, 3) ListNode(1, ListNode(8, ListNode (27, None)))