add: type assertion

interfaces/05-assertion/main.go

@@ -13,16 +13,19 @@ func main() {
 		minecraft = game{title: "minecraft", price: 20}
 		tetris    = game{title: "tetris", price: 5}
 		rubik     = puzzle{title: "rubik's cube", price: 5}
+		yoda      = toy{title: "yoda", price: 150}
 	)
 
 	var store list
-	store = append(store, &minecraft, &tetris, mobydick, &rubik)
+	store = append(store, &minecraft, &tetris, mobydick, rubik, &yoda)
 
+	// #2
 	store.discount(.5)
 	store.print()
 
-	// minecraft.discount(.5)
-	// minecraft.print()
+	// #1
+	// var p printer
+	// p = &tetris
+	// tetris.discount(.5)
+	// p.print()
 }
-
-// store.discount()