import zipfile

def main():
    open_order = ['90052.txt']
    infile = open('channel/90052.txt', 'r')
    while infile:
        line = infile.readline().split()
        if line[-1].isdigit():
            open_order.append(line[-1] + '.txt')
            infile = open('channel/' + line[-1] + '.txt')
    comments = ''
    inzip = zipfile.ZipFile('channel.zip')
    for file in open_order:
        zipcomment = inzip.getinfo(file).comment
        comments += zipcomment
    print comments

main()

this is the error:
    if line[-1].isdigit():
IndexError: list index out of range