halokid/codeBox: book_sample/Concurrency-in-Go/c4.go; 10 LoC

Found a possible issue in [halokid/codeBox](https://www.github.com/halokid/codeBox) at [book_sample/Concurrency-in-Go/c4.go](https://github.com/halokid/codeBox/blob/c28908b9968c264515dded12d146171c74b8f07f/book_sample/Concurrency-in-Go/c4.go#L14-L23)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first
issue it finds, so please do not limit your consideration to the contents of the below message.

> range-loop variable salutation used in defer or goroutine at line 20

[Click here to see the code in its original context.](https://github.com/halokid/codeBox/blob/c28908b9968c264515dded12d146171c74b8f07f/book_sample/Concurrency-in-Go/c4.go#L14-L23)

Click here to show the 10 line(s) of Go which triggered the analyzer.

```go
for _, salutation := range []string{"hello", "greetings", "good day"} {
//for i := 0; i < 10; i++ {
wg3.Add(1)

go func() {
defer wg3.Done()
fmt.Println(salutation) // 抢占式输出slice的内容
//fmt.Println(i) // 输出i之后，表示for里面添加 goroutine， 并不是顺序输出的
}()
}

```

Leave a reaction on this issue to contribute to the project by classifying this instance as a **Bug** :-1:, **Mitigated** :+1:, or **Desirable Behavior** :rocket:
See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: c28908b9968c264515dded12d146171c74b8f07f