static function create($mementoKey, $data = array(), $isMainKey = false, $mainKey = null)
 {
     if (is_array($mementoKey)) {
         $mementoKey = eZOperationMemento::createKey($mementoKey);
     }
     $serializedData = serialize($data);
     return new eZOperationMemento(array('id' => null, 'main' => $isMainKey ? 1 : 0, 'memento_key' => $mementoKey, 'main_key' => $isMainKey ? $mementoKey : $mainKey, 'memento_data' => $serializedData));
 }