// Validate implements cli.Validator interface func (argv *argT) Validate(ctx *cli.Context) error { if argv.Age < 0 || argv.Age > 300 { return fmt.Errorf("age %d out of range", argv.Age) } if argv.Gender != "male" && argv.Gender != "female" { return fmt.Errorf("invalid gender %s", ctx.Color().Yellow(argv.Gender)) } return nil }