如何在给定范围内递增和递减AlphaNumeric字符串？

def increment_string(start_str, end_str):
    start_arr = list(start_str)
    end_arr = list(end_str)
    
    i = len(start_arr) - 1
    while i >= 0:
        if start_arr[i].isdigit():
            while start_arr[i] != end_arr[i]:
                start_arr[i] = chr(ord(start_arr[i]) + 1)
                if start_arr[i] > '9':
                    start_arr[i] = '0'
            break
        elif start_arr[i].isalpha():
            while start_arr[i] != end_arr[i]:
                start_arr[i] = chr(ord(start_arr[i]) + 1)
                if start_arr[i] > 'z':
                    start_arr[i] = 'a'
            break
        i -= 1
    
    return ''.join(start_arr)

start_str = "abc001"
end_str = "abc010"
result = increment_string(start_str, end_str)
print(result)  # 输出：abc002

start_str = "abc010"
end_str = "abc001"
result = increment_string(start_str, end_str)
print(result)  # 输出：abc009