flag包，用于解析命令行参数，代码示例如下

package main

import (
    "flag"
    "fmt"
)

func main(){
    var name = flag.String("name","chancel","input your name")
    var age = flag.Int("age",10,"input your age")
	flag.Parse()
    fmt.Println("Hello ",*name," age:",*age)
}
// 输出
➜ go run main.go --name demo --age 18
Hello  demo  age: 18