def mergeTwoLists(self, l1, l2):
        dummy = ListNode(0)
        dummy.next = l1

        pre = dummy
        the_other = l2
        while pre and pre.next:
            cur = pre.next
            if the_other and cur.val>the_other.val:
                # insert
                temp = the_other.next
                pre.next, the_other.next = the_other, cur

                the_other = temp  # advance the_other
            pre = pre.next


        # dangling list
        if the_other:
            pre.next = the_other  # appending

        return dummy.next
Returns the number of tickets.
dataset/ETHPy150Open algorhythms/LeetCode/022 Merge k Sorted Lists.py/Solution.mergeTwoLists--crossover with--dataset/ETHPy150Open getlogbook/logbook/logbook/ticketing.py/SQLAlchemyBackend.count_tickets