update book code

eBook/examples/chapter_10/method1.go

@@ -0,0 +1,29 @@
+package main
+
+import "fmt"
+
+type TwoInts struct {
+	a int
+	b int
+}
+
+func main() {
+	two1 := new(TwoInts)
+	two1.a = 12
+	two1.b = 10
+
+	fmt.Printf("The sum is: %d\n", two1.AddThem())
+	fmt.Printf("Add them to the param: %d\n", two1.AddToParam(20))
+	
+	// literal:
+	two2 := TwoInts{3, 4}
+	fmt.Printf("The sum is: %d\n", two2.AddThem())
+}
+
+func (tn *TwoInts) AddThem() int {
+	return tn.a + tn.b
+}
+
+func (tn *TwoInts) AddToParam(param int) int {
+	return tn.a + tn.b + param
+}