add timing tests to day5

utils/timing/timing.go

@@ -0,0 +1,14 @@
+package timing
+
+import "time"
+
+func TimeFunction(fn func(), trials int) time.Duration {
+	startTime := time.Now()
+
+	for i := 0; i < trials; i++ {
+		fn()
+	}
+	endTime := time.Now()
+
+	return endTime.Sub(startTime)
+}