code: func (sys *System) detectPackage(c *cli.Context) {
  	p := c.GlobalString("package")
  	if p != "deb" && p != "apk" && p != "pacman" && p != "rpm" {
  		p = DetectPackageManager()
  	}
  	switch p {
  	case "deb":
  		sys.NewPackage = NewDebPackage
  	case "apk":
  		sys.NewPackage = NewAlpinePackage
  	case "pacman":
  		sys.NewPackage = NewPacmanPackage
  	default:
  		sys.NewPackage = NewRpmPackage
  	}
  }
docs: // detectPackage adds the correct package creation function to a System struct