Python 2.7: Convert one line into lines of 260 characters and remove all character before '_' in each line -

i must convert infile lines of 260 characters , remove content before (including character) '_'

i have been looking around hours , found way convert 260 characters.

lines = infile.readlines() [line[i:i+n] in lines(0, len(line), 640)] 

and found lot of examples wrt removing characters string or characters after argument.

please me out here...

lines = infile.readlines() [line[i:i+n] in lines(0, len(line), 640)] line.split("_")[1]