code: public function lock(string $sessionIdentifier): bool
      {
          if (in_array($sessionIdentifier, self::$lockedIdentifiers)) {
              return true;
          }
  
          self::$lockedIdentifiers[] = $sessionIdentifier;
  
          return true;
      }
docs: Asks the drive to lock the session storage
  
  @param string $sessionIdentifier The session identifier to be locked
  @return bool