뒤집어 재배열. 문장 부호 빼고

invert.py

import string

def invert(str):
    result = list(str)
    j = len(str)-1
    for i in range(0, len(str)):
        if(str[i] in string.punctuation or str[i] == ' '):
            continue

        k = 0
        while(result[j-k] in string.punctuation or result[j-k] == ' '):
            k += 1
        if(str[j-k].isupper()):
            result[j-k] = str[i].upper()
        else:
            result[j-k] = str[i].lower()
        j = j-k-1

    return ''.join(result)