public function clear()
    {
        $params = [
            'index' => $this->_esindex,
            'type' => $this->_estype,
            'body' => [
                'query' => [
                    'match_all' => []
                ]
            ]
        ];
        $query = $this->_es->deleteByQuery($params); 
        // return $query['_indices']['tweets']['_shards']['successful'];
        $result = true;
        return $result;
    }