import random

class LinkedListNode:
    def __init__(self, value, next_node=None, prev_node=None):
        self.value = value
        self.next = next_node
        self.prev = prev_node

    def __str__(self):
        return str(self.value)


class LinkedList:
    def __init__(self, values=None):
        self.head = None
        self.tail = None
        if values is not None:
            self.add_multiple(values)

    def __iter__(self):
        current = self.head
        while current:
            yield current
            current = current.next

    def __str__(self):
        values = [str(x) for x in self]
        return " -> ".join(values)

    def __len__(self):
        result = 0
        node = self.head
        while node:
            result += 1
            node = node.next
        return result

    def values(self):
        return [x.value for x in self]

    def add(self, value):
        if self.head is None:
            self.tail = self.head = LinkedListNode(value)
        else:
            self.tail.next = LinkedListNode(value)
            self.tail = self.tail.next
        return self.tail

    def add_to_beginning(self, value):
        if self.head is None:
            self.tail = self.head = LinkedListNode(value)
        else:
            self.head = LinkedListNode(value, self.head)
        return self.head

    def add_multiple(self, values):
        for v in values:
            self.add(v)

    @classmethod
    def generate(cls, k, min_value, max_value):
        return cls(random.choices(range(min_value, max_value), k=k))
        
def twolistsum(ll1, ll2):
  num1 = ""
  for ll in ll1:
    num1 += str(ll.value)
  num2 = ""
  for ll in ll2:
    num2 += str(ll.value)
  ans = int(num1 + num2)
  
  values = [int(n) for n in str(ans)]
  
  ansll = LinkedList()
  ansll.add_multiple(values)
  
  return ansll
$ python -u "/Users/wafuwafu13/Deskt
op/python_playground/index.py"
7 -> 4 -> 4 -> 7
1 -> 1 -> 3
7 -> 4 -> 4 -> 7 -> 1 -> 1 -> 3