code: func NewOVAFile(filename string) (*OVAFile, error) {
  	f, err := os.Open(filename)
  	if err != nil {
  		return nil, err
  	}
  	tarFile := tar.NewReader(f)
  	return &OVAFile{filename: filename, file: f, tarFile: tarFile}, nil
  }
docs: // NewOVAFile creates a new OVA file reader