如何使用自定义字符集递增字符串

def increment_string(charset, string, max_length):
    char_list = list(string)
    charset_len = len(charset)
    for i in range(len(char_list)-1, -1, -1):
        char = char_list[i]
        if char == charset[-1]:
            char_list[i] = charset[0]
            if i == 0:
                char_list.insert(0, charset[0])
        else:
            char_list[i] = charset[charset.index(char)+1]
            break
    return "".join(char_list[:max_length])

charset = "0123456789"
string = "000"
max_length = 5

new_string = increment_string(charset, string, max_length)
print(new_string)  # 输出："001"