code: public function show($accountId = null)
      {
          $options = [
          ];
  
          if (!is_null($accountId)) {
              $options['account_id'] = $accountId;
          }
  
          return $this->factory->collection(
              $this->client->get(
                  "rooms/{$this->roomId}/files",
                  $options
              )
          );
      }
docs: @param null $accountId
  
  @return CollectionInterface