fix up movies index route [wip]

unwind-ui/src/utils.ts

@@ -1,3 +1,18 @@
 export function is_object(x) {
   return x !== null && typeof x === "object" && !Array.isArray(x)
 }
+
+export function sum(nums) {
+  return nums.reduce((s, n) => s + n, 0)
+}
+
+export function mean(nums) {
+  return sum(nums) / nums.length
+}
+
+export function pstdev(nums, mu=null) {
+  if (mu === null) {
+    mu = mean(nums)
+  }
+  return Math.sqrt(mean(nums.map((n) => (n - mu) ** 2)))
+}