def problem_two(limit=4000000):
"""
Find the sum of all the even-valued terms in the fibonacci sequence
which do not exceed four million.
"""
even_fibs = (fib(n) for n in count() if fib(n) % 2 == 0)
return sum(takewhile(lambda x: x < limit, even_fibs))
def problem_25():
"""
What is the first term in the Fibonacci sequence to contain 1000 digits?
"""
digits = lambda x: len(str(x))
for n in count(1):
num = fib(n)
if digits(num) < 1000: continue
return n
