def mangle(line):
    line = string.strip(line)
    if (len(line) == 0):
        return (None, None)
    if (line[0] == '#'):
        return (None, line)
    checksumpos = string.find(line, '?')
    commentpos = string.find(line, '#')
    if (commentpos < 0):
        comment = None
    else:
        comment = ' ' + line[commentpos:]
        line = string.strip(line[0:commentpos])
    if (checksumpos == 9):
        line = string.strip(line[0:checksumpos])
        if (commentpos < 0):
            comment = ' ' + '# generated check sum'
        else:
            comment = comment + ' ' + 'Generated check sum'
        sum = 0
        count = 0
        for ix in line:
            sum = sum + (10 - count) * string.atoi(ix)
            count = count + 1
        sum = sum % 11
        if (sum != 0):
            sum = 11 - sum
        if (sum == 10):
            line = line + 'X'
        else:
            line = line + string.digits[sum]
    return (line, comment)