public function get_groups($page_size = nil, $page = 1){
		$client = new \GuzzleHttp\Client();

		$response = $client->get($this->api_endpoint.'issuer/all_groups?page_size=' . $page_size . '&page=' . $page, array('headers' =>  array('Authorization' => 'Token token="'.$this->getAPIKey().'"')));

		$result = json_decode($response->getBody());
		return $result;
	}