added calendar from chap 10

playground/calendar.go

@@ -0,0 +1,6 @@
+// from chapter 10
+package main
+
+func calendar() {
+
+}

playground/playground.go

@@ -110,6 +110,12 @@ func main() {
 				fuel()
 			},
 		},
+		{
+			name: "Calendar",
+			launchFunction: func() {
+				calendar()
+			},
+		},
 	}
 	menu := wmenu.NewMenu("Choose a program.")
 	menu.Action(func(opts []wmenu.Opt) error {