1def merge_two_lists(list1, list2):
2 dummy = ListNode(0)
3 curr = dummy
4 while list1 and list2:
5 if list1.val <= list2.val:
6 curr.next = list1; list1 = list1.next
7 curr.next = list2; list2 = list2.next
8 curr = curr.next
9 curr.next = list1 or list2
10 return dummy.next