https://docs.python.org/3.5/tutorial/errors.html


for arg in sys.argv[1:]:
    try:
        f = open(arg, 'r')
    except IOError:
        print('cannot open', arg)
    else:
        print(arg, 'has', len(f.readlines()), 'lines')
        f.close()


Although IOError is still available as an alias to OSError, it should not be used in the tutorial, I believe.