mapdev\FacebookMessenger\MessengerApi::callApi PHP Method

    public function callApi($path, $data, $type = self::POST, $json = true)
    {
        if (!$this->checkToken()) {
            throw CouldNotSendNotification::invalidFacebookToken();
        }
        try {
            if ($json) {
                $response = $this->client->request($type, $this->api_url . $path, ['query' => ['access_token' => $this->token], 'json' => $data]);
            } else {
                $data['access_token'] = $this->token;
                $response = $this->client->request($type, $this->api_url . $path, ['query' => $data]);
            }
            if ($response->getStatusCode() == 200) {
                return json_decode($response->getBody());
            } else {
                throw CouldNotSendNotification::invalidStatusCode($response->getStatusCode());
            }
        } catch (ClientException $ex) {
            throw CouldNotSendNotification::facebookResponseError($ex);
        } catch (\Exception $ex) {
            throw CouldNotSendNotification::couldNotCommunicateWithFacebook($ex);
        }
    }