code: func VerifyChart(path string, keyring string) (*provenance.Verification, error) {
  	// For now, error out if it's not a tar file.
  	if fi, err := os.Stat(path); err != nil {
  		return nil, err
  	} else if fi.IsDir() {
  		return nil, errors.New("unpacked charts cannot be verified")
  	} else if !isTar(path) {
  		return nil, errors.New("chart must be a tgz file")
  	}
  
  	provfile := path + ".prov"
  	if _, err := os.Stat(provfile); err != nil {
  		return nil, fmt.Errorf("could not load provenance file %s: %s", provfile, err)
  	}
  
  	sig, err := provenance.NewFromKeyring(keyring, "")
  	if err != nil {
  		return nil, fmt.Errorf("failed to load keyring: %s", err)
  	}
  	return sig.Verify(path, provfile)
  }
docs: // VerifyChart takes a path to a chart archive and a keyring, and verifies the chart.
  //
  // It assumes that a chart archive file is accompanied by a provenance file whose
  // name is the archive file name plus the ".prov" extension.