public static function all()
    {
        $command = 'grep --include="*.php" --files-with-matches -r "class" '.app_path();

        exec($command, $files);

        return collect($files)->map(function($file) {
            return self::convertFileToClass($file);
        })->filter(function($class) {
            return class_exists($class) && is_subclass_of($class, Model::class);
        });
    }