public function getVisa(File $file)
    {
        $visa = new Visa();

        if (!$this->isEnabled()) {
            return $visa;
        }

        foreach ($this->checkers as $checker) {
            if ($checker->isApplicable($file)) {
                $visa->addResponse($checker->check($this->app['orm.em'], $file));
            }
        }

        return $visa;
    }