Buat interface NotificationService dengan method send(string $message): string. Buat class EmailNotification yang mengimplementasikan interface tersebut dan return "Email: [message]". Bind interface ke implementasi di service provider.

Hint

• Service Container me-resolve dependencies secara otomatis.
• Bind interface ke implementasi di ServiceProvider.
• $this->app->bind(NotificationService::class, EmailNotification::class);