lazy

lazy.py

def ifilter(funcao, seq):
	for x in seq:
		if funcao(x):
			yield x

def take(seq, n):
	i = 0
	for x in seq:
		if i < n:
			yield x
			i += 1
		else:
			break

def naturais():
	i = 0
	while True:
		yield i
		i += 1

def pares():
	return ifilter(lambda x: x % 2 == 0, naturais())


print sum(take(pares(), 10))