Update 11.1.md

eBook/11.1.md

@@ -67,12 +67,12 @@ func main() {
 	sq1 := new(Square)
 	sq1.side = 5
 
-	// var areaIntf Shaper
-	// areaIntf = sq1
+	var areaIntf Shaper
+	areaIntf = sq1
 	// shorter,without separate declaration:
 	// areaIntf := Shaper(sq1)
 	// or even:
-	areaIntf := sq1
+	// areaIntf := sq1
 	fmt.Printf("The square has area: %f\n", areaIntf.Area())
 }
 ```