code: func (o *Options) SetPublicKeyPEM(pembytes []byte) error {
  	block, _ := pem.Decode(pembytes)
  	if block == nil {
  		return errors.New("couldn't parse PEM data")
  	}
  
  	pub, err := x509.ParsePKIXPublicKey(block.Bytes)
  	if err != nil {
  		return err
  	}
  	o.PublicKey = pub
  	return nil
  }
docs: // SetPublicKeyPEM is a convenience method to set the PublicKey property
  // used for checking a completed update's signature by parsing a
  // Public Key formatted as PEM data.