public function put(array $arr_docs)
    {
        $obj_request = new IndexDocumentRequest();
        $obj_params = $this->prepareRequestParams($obj_request);

        // Other index specs: consistency, mode, name, namespace, source, version
        $obj_mapper = new Mapper();
        foreach($arr_docs as $obj_doc) {
            $obj_mapper->toGoogle($obj_doc, $obj_params->addDocument());
        }
        $this->execute('IndexDocument', $obj_request, new IndexDocumentResponse());
    }