我应该如何输入一个也可以是无穷大的整型变量？

def add_large_numbers(num1, num2):
    # 将两个整数转换为字符串
    str1 = str(num1)
    str2 = str(num2)
    
    # 获取两个字符串的长度
    len1 = len(str1)
    len2 = len(str2)
    
    # 将两个字符串的长度补齐，使其相等
    if len1 > len2:
        str2 = '0' * (len1 - len2) + str2
    else:
        str1 = '0' * (len2 - len1) + str1
    
    # 逐位相加，进位处理
    carry = 0
    result = ''
    for i in range(len(str1)-1, -1, -1):
        digit_sum = int(str1[i]) + int(str2[i]) + carry
        digit = digit_sum % 10
        carry = digit_sum // 10
        result = str(digit) + result
    
    # 如果最高位有进位，需要将进位加到结果中
    if carry > 0:
        result = str(carry) + result
    
    return result

# 示例用法
num1 = '123456789012345678901234567890'
num2 = '987654321098765432109876543210'
result = add_large_numbers(num1, num2)
print(result)