update book code

eBook/exercises/chapter_13/recover_divbyzero.go

@@ -0,0 +1,34 @@
+// recover_divbyzero.go
+package main
+
+import (
+	"fmt"
+)
+
+func badCall() {
+  a, b := 10, 0
+  n := a / b
+  fmt.Println(n)
+}
+
+func test() {
+   defer func() { 
+    if e := recover(); e != nil {
+       fmt.Printf("Panicing %s\r\n", e);
+    }
+   
+    }()
+    badCall()
+    fmt.Printf("After bad call\r\n");
+}
+
+func main() {
+   fmt.Printf("Calling test\r\n");
+   test()
+   fmt.Printf("Test completed\r\n");
+}
+/* Output:
+Calling test
+Panicing runtime error: integer divide by zero
+Test completed
+*/