| # https://projecteuler.net/problem=2 | |
| # Sum the even Fibonacci terms not exceeding 4,000,000. | |
| # Recursive function calling, generators and Python idioms | |
| def fib(): | |
| a, b = 1, 2 | |
| while True: | |
| yield a | |
| a, b = b, a + b | |
| def evens(it): | |
| for x in it: | |
| if x % 2 == 0: | |
| yield x | |
| def upto(limit, it): | |
| for x in it: | |
| if x > limit: | |
| return | |
| yield x | |
| def euler2(limit=4000000): | |
| return sum(evens(upto(limit, fib()))) | |
| print(euler2()) | |