fix: coding style and file format for all example.

eBook/examples/chapter_11/duck_dance.go

@@ -1,32 +1,32 @@
-package main
-
-import "fmt"
-
-type IDuck interface {
-	Quack()
-	Walk()
-}
-
-func DuckDance(duck IDuck) {
-	for i := 1; i <= 3; i++ {
-		duck.Quack()
-		duck.Walk()
-	}
-}
-
-type Bird struct {
-	// ...
-}
-
-func (b *Bird) Quack() {
-	fmt.Println("I am quacking!")
-}
-
-func (b *Bird) Walk()  {
-	fmt.Println("I am walking!")
-}
-
-func main() {
-	b := new(Bird)
-	DuckDance(b)
-}
+package main
+
+import "fmt"
+
+type IDuck interface {
+	Quack()
+	Walk()
+}
+
+func DuckDance(duck IDuck) {
+	for i := 1; i <= 3; i++ {
+		duck.Quack()
+		duck.Walk()
+	}
+}
+
+type Bird struct {
+	// ...
+}
+
+func (b *Bird) Quack() {
+	fmt.Println("I am quacking!")
+}
+
+func (b *Bird) Walk() {
+	fmt.Println("I am walking!")
+}
+
+func main() {
+	b := new(Bird)
+	DuckDance(b)
+}