public function getMP3($id)
 {
     $mp3 = MP3::published()->whereId($id)->first();
     if ($mp3->price == 'paid') {
         if (!Auth::check()) {
             return Redirect::to('/login')->withMessage(Config::get('site.message.login'));
         }
         if (Auth::check()) {
             $user = Auth::user();
             $bought = MP3Sold::whereUserId($user->id)->whereMp3Id($mp3->id)->first();
             if (!$bought && !$user->is_admin()) {
                 return Redirect::to("/mp3/buy/{$mp3->id}")->withMessage(Config::get('site.message.must-buy'));
             }
         }
     }
     TKPM::download($mp3);
 }