subtree(users/wpcarro): docking briefcase at '24f5a642'

git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c
git-subtree-split: 24f5a642af
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789

users/wpcarro/scratch/facebook/interview-cake/nth-fibonacci.py

@@ -0,0 +1,6 @@
+def fib(n):
+    cache = (0, 1)
+    for _ in range(n):
+        a, b = cache
+        cache = (b, a + b)
+    return cache[0]