def euler_25(n):
g = lib.fib_gen(0, 1)
pred = lambda y: len(str(y)) == n
return next((i, x) for (i, x) in enumerate(g) if pred(x))[0]
def euler_2():
g = lib.fib_gen(1, 2)
vals = (x for x in takewhile(lambda x: x < 4000000, g) if x % 2 == 0)
return sum(vals)