fix csv output line

[binary1230]

For the CSV output function

General Python note: the best practice for this would be to say

with open(filename, 'w') as f:
    f.writelines(lines)

Note that even if you were writing the lines individually instead of using writelines there's no reason to use os.linesep because Python will automatically convert \n to the appropriate line ending if you open in w mode. If you wanted to NOT do that, you would open in wb mode.