/**
  * Choose which usernames to query next
  * If there are no free usernames at the moment, increae the length of the possible usernames by 1
  *
  * @return mixed
  */
 private function selectUsernames()
 {
     $toCheck = TwitterUser::neverQueried();
     if ($toCheck->count() == 0) {
         return TwitterUser::orderBy('last_checked', 'asc')->take(100)->get()->pluck('username');
     }
     return TwitterUser::neverQueried()->take(100)->get()->pluck('username');
 }