add_Two_number

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Example:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

My solution:
# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        
        
        add_before=0
        count=0
        while l1.next!=None and l2.next!=None:
            value1=l1.val
            value2=l2.val
            value=value1+value2+add_before
            if value>=10:
                value=value-10
                add_before=1
            else:
                add_before=0
            if count==0:
                start_node=ListNode(value)
                tmp_node=start_node
            else:
                tmp1_node=ListNode(value)
                tmp_node.next=tmp1_node
                tmp_node=tmp1_node
            count+=1
            l1=l1.next
            l2=l2.next
        #Special occasion for last digit
        value1=l1.val
        value2=l2.val
        value=value1+value2+add_before
        if value>=10:
            value=value-10
            add_before=1
        else:
            add_before=0  
        if count==0:
            start_node=ListNode(value)
            tmp_node=start_node
        else:
            tmp1_node=ListNode(value)
            tmp_node.next=tmp1_node
            tmp_node=tmp1_node
        if add_before==1 and l1.next==None and l2.next==None:
            tmp1_node=ListNode(add_before)
            tmp_node.next=tmp1_node
            tmp_node=tmp1_node            
        if l1.next==None and l2.next==None:
            return start_node
        if l1.next==None:
            l_temp=l2
        elif l2.next==None:
            l_temp=l1
        l_temp=l_temp.next

        while l_temp.next!=None:
            value=l_temp.val
           
            value=value+add_before
            if value>=10:
                add_before=1
                value=value-10
            else:
                add_before=0
                
            tmp1_node=ListNode(value)
            tmp_node.next=tmp1_node
            tmp_node=tmp1_node            
            l_temp=l_temp.next
        value=l_temp.val
        value=value+add_before
        if value>=10:
            value=value-10
            add_before=1
        else:
            add_before=0   
        tmp1_node=ListNode(value)
        tmp_node.next=tmp1_node
        tmp_node=tmp1_node
        if add_before==1:
            tmp1_node=ListNode(add_before)
            tmp_node.next=tmp1_node
            tmp_node=tmp1_node            
                
            
        return start_node
                
        
            
 Solution:
 https://leetcode.com/problems/add-two-numbers/solution/