fix: coding style and file format for all example.

eBook/examples/chapter_10/method2.go

@@ -1,16 +1,16 @@
-package main
-
-import "fmt"
-
-type IntVector []int
-
-func (v IntVector) Sum() (s int) {
-	for _, x := range v {
-		s += x
-	}
-	return
-}
-
-func main() {
-	fmt.Println(IntVector{1, 2, 3}.Sum())  // Output: 6
-}
+package main
+
+import "fmt"
+
+type IntVector []int
+
+func (v IntVector) Sum() (s int) {
+	for _, x := range v {
+		s += x
+	}
+	return
+}
+
+func main() {
+	fmt.Println(IntVector{1, 2, 3}.Sum()) // Output: 6
+}