code: public function save(string $sessionIdentifier, string $sessionData): void
      {
          self::$files[$sessionIdentifier] = [
              'data' => $sessionData,
              'time' => microtime(true)
          ];
      }
docs: Saves the encrypted session data to the storage.
  
  @param  string $sessionIdentifier The string used to identify the session data.
  @param  string $sessionData       The encrypted session data.
  @return void