code: func (tz *TzArchive) extractFile(f *File, tr *tar.Reader) error {
  	if !tz.isHasWriter {
  		for _, h := range tz.ReadCloser.File {
  			if f.Name == h.Name {
  				return extractFile(h, tr, f.absPath)
  			}
  		}
  	}
  
  	return cae.Copy(f.Name, f.absPath)
  }
docs: // extractFile extracts file from TzArchive to file system.