go flag的使用

package mainimport "flag"import "fmt"import "strconv"type percentage float32func (p *percentage) Set(s string) error {  v, err := strconv.ParseFloat(s, 32)  *p = percentage(v)  return err}func (p *percentage) String() string { return fmt.Sprintf("%f", *p) }func main() {  namePtr := flag.String("name", "lyh", "user's name")  agePtr := flag.Int("age", 22, "user's age")  vipPtr := flag.Bool("vip", true, "is a vip user")  var email string  flag.StringVar(&email, "email", "[e-mail]", "user's email")  var pop percentage  flag.Var(&pop, "pop", "popularity")  flag.Parse()  others := flag.Args()  fmt.Println("name:", *namePtr)  fmt.Println("age:", *agePtr)  fmt.Println("vip:", *vipPtr)  fmt.Println("pop:", pop)  fmt.Println("email:", email)  fmt.Println("other:", others)}