func ensure(binary, install string) error {
	if _, err := exec.LookPath(binary); err != nil {
		return fmt.Errorf("%s: %s", binary, install)
	}
	return nil
}
func ensure(binary, install string) error {
	if _, err := exec.LookPath(binary); err != nil {
		return fmt.Errorf("%s: %s", binary, install)
	}
	return nil
}
// ensure will ensure binary is on path or return an error with install message.