code: func validateBundledVersions(bundledVersions SupportedVersions, binDir string) error {
  	for _, v := range bundledVersions {
  		for _, binaryName := range []string{"etcd", "etcdctl"} {
  			fn := filepath.Join(binDir, fmt.Sprintf("%s-%s", binaryName, v))
  			if _, err := os.Stat(fn); err != nil {
  				return fmt.Errorf("failed to validate '%s' binary exists for bundled-version '%s': %v", fn, v, err)
  			}
  
  		}
  	}
  	return nil
  }
docs: // validateBundledVersions checks that 'etcd-<version>' and 'etcdctl-<version>' binaries exist in the binDir
  // for each version in the bundledVersions list.