code: func OpenZipReader(r io.ReaderAt, size int64) (*Apk, error) {
  	zipreader, err := zip.NewReader(r, size)
  	if err != nil {
  		return nil, err
  	}
  	apk := &Apk{
  		zipreader: zipreader,
  	}
  	if err = apk.parseManifest(); err != nil {
  		return nil, errors.Wrap(err, "parse-manifest")
  	}
  	if err = apk.parseResources(); err != nil {
  		return nil, err
  	}
  	return apk, nil
  }
docs: // OpenZipReader has same arguments like zip.NewReader