code: func (s *FileStorage) LoadSite(domain string) (*SiteData, error) {
  	var err error
  	siteData := new(SiteData)
  	siteData.Cert, err = s.readFile(s.siteCertFile(domain))
  	if err != nil {
  		return nil, err
  	}
  	siteData.Key, err = s.readFile(s.siteKeyFile(domain))
  	if err != nil {
  		return nil, err
  	}
  	siteData.Meta, err = s.readFile(s.siteMetaFile(domain))
  	if err != nil {
  		return nil, err
  	}
  	return siteData, nil
  }
docs: // LoadSite implements Storage.LoadSite by loading it from disk. If it is not
  // present, an instance of ErrNotExist is returned.