How to use the algorithms.linkedlist.add_two_numbers.Node function in algorithms

def convert_to_list(number: int) -> Node:
    """
        converts a positive integer into a (reversed) linked list.
        for example: give 112
        result 2 -> 1 -> 1
    """
    if number >= 0:
        head = Node(0)
        current = head
        remainder = number % 10
        quotient = number // 10

        while quotient != 0:
            current.next = Node(remainder)
            current = current.next
            remainder = quotient % 10
            quotient //= 10
        current.next = Node(remainder)
        return head.next
    else:
        print("number must be positive!")

def add_two_numbers(left: Node, right: Node) -> Node:
    head = Node(0)
    current = head
    sum = 0
    while left or right:
        print("adding: ", left.val, right.val)
        sum //= 10
        if left:
            sum += left.val
            left = left.next
        if right:
            sum += right.val
            right = right.next
        current.next = Node(sum % 10)
        current = current.next
    if sum // 10 == 1:
        current.next = Node(1)
    return head.next

def add_two_numbers(left: Node, right: Node) -> Node:
    head = Node(0)
    current = head
    sum = 0
    while left or right:
        print("adding: ", left.val, right.val)
        sum //= 10
        if left:
            sum += left.val
            left = left.next
        if right:
            sum += right.val
            right = right.next
        current.next = Node(sum % 10)
        current = current.next
    if sum // 10 == 1:
        current.next = Node(1)
    return head.next

result = convert_to_str(add_two_numbers(number3, number4))
        self.assertEqual("2101", result)

        # 3. test case
        number5 = Node(1)
        number6 = Node(0)
        result = convert_to_str(add_two_numbers(number5, number6))
        self.assertEqual("1", result)

        # 4. test case
        number7 = Node(9)
        number7.next = Node(1)
        number7.next.next = Node(1)
        number8 = Node(1)
        number8.next = Node(0)
        number8.next.next = Node(1)
        result = convert_to_str(add_two_numbers(number7, number8))
        self.assertEqual("022", result)

def test_add_two_numbers(self):
        # 1. test case
        number1 = Node(2)
        number1.next = Node(4)
        number1.next.next = Node(3)
        number2 = Node(5)
        number2.next = Node(6)
        number2.next.next = Node(4)
        result = convert_to_str(add_two_numbers(number1, number2))
        self.assertEqual("708", result)

        # 2. test case
        number3 = Node(1)
        number3.next = Node(1)
        number3.next.next = Node(9)
        number4 = Node(1)
        number4.next = Node(0)
        number4.next.next = Node(1)
        result = convert_to_str(add_two_numbers(number3, number4))

def test_convert_to_str(self):
        number1 = Node(2)
        number1.next = Node(4)
        number1.next.next = Node(3)
        self.assertEqual("243", convert_to_str(number1))

def test_convert_to_str(self):
        number1 = Node(2)
        number1.next = Node(4)
        number1.next.next = Node(3)
        self.assertEqual("243", convert_to_str(number1))

def test_add_two_numbers(self):
        # 1. test case
        number1 = Node(2)
        number1.next = Node(4)
        number1.next.next = Node(3)
        number2 = Node(5)
        number2.next = Node(6)
        number2.next.next = Node(4)
        result = convert_to_str(add_two_numbers(number1, number2))
        self.assertEqual("708", result)

        # 2. test case
        number3 = Node(1)
        number3.next = Node(1)
        number3.next.next = Node(9)
        number4 = Node(1)
        number4.next = Node(0)
        number4.next.next = Node(1)
        result = convert_to_str(add_two_numbers(number3, number4))
        self.assertEqual("2101", result)

        # 3. test case
        number5 = Node(1)

def test_convert_to_str(self):
        number1 = Node(2)
        number1.next = Node(4)
        number1.next.next = Node(3)
        self.assertEqual("243", convert_to_str(number1))

def test_add_two_numbers(self):
        # 1. test case
        number1 = Node(2)
        number1.next = Node(4)
        number1.next.next = Node(3)
        number2 = Node(5)
        number2.next = Node(6)
        number2.next.next = Node(4)
        result = convert_to_str(add_two_numbers(number1, number2))
        self.assertEqual("708", result)

        # 2. test case
        number3 = Node(1)
        number3.next = Node(1)
        number3.next.next = Node(9)
        number4 = Node(1)
        number4.next = Node(0)
        number4.next.next = Node(1)
        result = convert_to_str(add_two_numbers(number3, number4))
        self.assertEqual("2101", result)

        # 3. test case
        number5 = Node(1)
        number6 = Node(0)
        result = convert_to_str(add_two_numbers(number5, number6))
        self.assertEqual("1", result)

        # 4. test case
        number7 = Node(9)