Golang 如何判断数组某个元素是否存在(isset)

package main 
import (
 "fmt"
 "os"
)
 
func main() {
 if os.Args[1] != "" {
 fmt.Println("aaa")
 } else {
 fmt.Println("bbb")
 } 
}

panic: runtime error: index out of range 
goroutine 1 [running]:
main.main()
 /root/workspace/go/testn.go:9 +0x100
exit status 2

package main 
import (
 "fmt"
 "os"
)
 
func main() {
 var target string        // 用来获取最终需要的os.Args[1]
 for k, v := range(os.Args) {
 if k == 1 {        // 假设需要获取os.Args[k], k = 1
 target = v
 }
 } 
 
 if target != "" {        // 不为空则表示os.Arg[1]存在
 fmt.Printf("os.Arg[1] = %s", target)  
 }
}

var jsonBlob = []byte(`[
{"Name": "Platypus", "Order": "Monotremata"}
]`)
type Animal struct {
Name string
Order string
ID
int
}
animals := &Animal{ID: -9999}
err := json.Unmarshal(jsonBlob, animals)
if err != nil {
fmt.Println("error:", err)
}
fmt.Printf("%+v", animals)

type NodeXXX struct {
Date string `json:"date"`
Count *int32 `json:"count"`
}