public function previous($fallback = false)
{
$referrer = $this->request->headers->get('referer');
$url = $referrer ? $this->to($referrer) : $this->getPreviousUrlFromSession();
if ($url) {
return $url;
} elseif ($fallback) {
return $this->to($fallback);
} else {
return $this->to('/');
}
}