protected function formatNotifiables($notifiables)
    {
        // Notifiables can be an anonymous function that returns an array
        if (is_callable($notifiables)) {
            $notifiables = $notifiables();
        }

        // Always make sure we have an array
        if (! is_array($notifiables)) {
            return [$notifiables];
        }

        return $notifiables;
    }