docs: function loadFromConfig(router, providers, sessionStore) {
    const sitesMap = siteService.sites(),
      siteHosts = _.uniq(_.map(sitesMap, 'host'));
  
    // iterate through the hosts
    _.each(siteHosts, hostname => {
      const sites = _.filter(sitesMap, {host: hostname}).sort(sortByDepthOfPath);
  
      addHost({
        router,
        hostname,
        sites,
        providers,
        sessionStore
      });
    });
  
    return router;
  }