1 class Solution(object):
 2     def reverseList(self, head):
 3         """
 4         :type head: ListNode
 5         :rtype: ListNode
 6         """
 7 
 8         prev = None
 9 
10         while head:
11             temp = head.next
12             head.next = prev
13             prev = head
14             head = temp
15 
16         return prev