added fuel for chapter nine

playground/fuel.go

@@ -0,0 +1,16 @@
+// part of chapter 9
+
+package main
+
+import "fmt"
+
+type Liters float64
+type Gallons float64
+
+func fuel() {
+	var carFuel Gallons
+	var busFuel Liters
+	carFuel = Gallons(10.0)
+	busFuel = Liters(240.0)
+	fmt.Println(carFuel, busFuel)
+}

playground/playground.go

@@ -104,6 +104,12 @@ func main() {
 				magazineSubscribers()
 			},
 		},
+		{
+			name: "Fuel",
+			launchFunction: func() {
+				fuel()
+			},
+		},
 	}
 	menu := wmenu.NewMenu("Choose a program.")
 	menu.Action(func(opts []wmenu.Opt) error {