[String] 같은 문자를 카운트해서 압축

#output string에 문자랑, 압축된 숫자를 바로 add
def compressWord(inputString):
    buffer = None
    result = ''
    cnt = 1

    for ch in inputString:
        if buffer is None:
            result += ch
            buffer = ch
        else:
            if buffer is ch:
                cnt += 1
            else:
                result += str(cnt)
                cnt = 1
                result += ch
                buffer = ch
    result += str(cnt)
    return result

if __name__ == '__main__':
    result=compressWord("aaaaabbcdddaaa")
    print(result) #output : a5b2c1d3a3