LinkedList.py

class ListNode(object):
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution(object):
    def addTwoNumbers(self, l1, l2):
        temp = []
        carry = 0
        while(not l1.val is None or not l2.val is None):
            if not l1.next is None: 
                l1 = l1.next
            else:
                l1.val = None
            if not l2.next is None:
                l2 = l2.next
            else:
                l2.val = None
        if carry == 1:
            temp.append(carry)
        return temp