public function all()
 {
     $taskListIds = $this->eventStore->uniqueAggregates();
     $taskLists = [];
     foreach ($taskListIds as $taskListId) {
         $taskListId = TaskListId::fromString($taskListId);
         $taskLists[] = $this->findById($taskListId);
     }
     return $taskLists;
 }