如何检索2个大数的和？

def addTwoBigNumbers(num1, num2):
    num1 = num1[::-1]  # 反转字符串
    num2 = num2[::-1]  # 反转字符串
    result = []
    carry = 0

    # 逐位相加
    for i in range(max(len(num1), len(num2))):
        digit1 = int(num1[i]) if i < len(num1) else 0
        digit2 = int(num2[i]) if i < len(num2) else 0
        sum = digit1 + digit2 + carry
        result.append(str(sum % 10))
        carry = sum // 10

    # 处理最高位的进位
    if carry > 0:
        result.append(str(carry))

    # 反转结果并返回
    return ''.join(result[::-1])

# 示例用法
num1 = "12345678901234567890"
num2 = "98765432109876543210"
sum = addTwoBigNumbers(num1, num2)
print(sum)