/**
  * @return bool
  */
 public function cleanup() : bool
 {
     $dayAgo = Carbon::create()->subDay();
     $set = ExportJob::where('created_at', '<', $dayAgo->format('Y-m-d H:i:s'))->whereIn('status', ['never_started', 'export_status_finished', 'export_downloaded'])->get();
     // loop set:
     /** @var ExportJob $entry */
     foreach ($set as $entry) {
         $key = $entry->key;
         $len = strlen($key);
         $files = scandir(storage_path('export'));
         /** @var string $file */
         foreach ($files as $file) {
             if (substr($file, 0, $len) === $key) {
                 unlink(storage_path('export') . DIRECTORY_SEPARATOR . $file);
             }
         }
         $entry->delete();
     }
     return true;
 }