Project Euler - Python - Problem 2

Python has some very cool iteration features - ive never used (or even heard of) generator functions before so I find this concept quite powerful.

from itertools import takewhile

def fibonacci():

    a,b=0,1

    while 1:

        yield a

        a,b=b,a+b

print(sum([i for i in takewhile(lambda z: z<4000000, fibonacci()) if i%2==0]))