Reibello AoC 6

#aoc2016_6.py
input_file_object = open("aoc16_input_6a.txt")
input_as_string = input_file_object.read()
input_file_object.close()

input_separated = input_as_string.split('\n')

cols = ['','','','','','','','']
msg = ''

def infrequent_char(text):
    charset = ''.join(sorted(text))
    mincount = len(text)
    minchar = None
    for item in charset.lower():
        charcount = text.count(item)
        if charcount < mincount :
            mincount = charcount
            minchar = item
    return minchar

for i in range(len(input_separated)):
    for j in range(len(cols)):
        cols[j] += cols[j].join(input_separated[i][j])

for x in range(len(cols)):
    res = infrequent_char(cols[x])
    msg += msg.join(res)