Adding control blocks examples.

control_blocks/main.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+  "fmt"
+  "math"
+)
+
+func pow(x, n, lim float64) float64 {
+  if v := math.Pow(x, n); v < lim {
+    return v
+  } else {
+    return lim
+  }
+}
+
+func main() {
+  fmt.Println(
+    pow(3, 2, 10),
+    pow(3, 3, 20),
+  )
+}