(x for x in open('super-large.txt')) # short-hand syntax for a generator ()
# better performing than a list comprehension []
# which loads everything into memory all at once
for line in (x for x in open('super-large.txt')):
pass # execute once for every line
for line in (x for x in open('super-large.txt') if int(x) % 100):
pass # execute once every 100 lines (instead of every line)