Problem 2

problem2.py

@@ -0,0 +1,9 @@
+def fib(limit=None):
+    a, b = 1, 2
+    yield a
+    yield b
+    while (not limit or a + b < limit):
+        a, b = b, a + b
+        yield b
+
+print(sum(n for n in fib(4_000_000) if n % 2 == 0))