private function sendRequest(string $method, string $uri, array $query = [], array $body = []) : array {
        $uri = sprintf('%s%s', $this->baseUrl, ltrim($uri, '/'));

        $options = [
            'headers' => [
                'Authorization' => (string) $this->authentication
            ],
            'http_errors' => false
        ];

        if (! empty($query)) {
            $options['query'] = $query;
        }

        if (! empty($body)) {
            $options['json'] = $body;
        }

        $response = $this->client->request(
            $method,
            $uri,
            $options
        );

        $json = json_decode((string) $response->getBody(), true);
        if ($json === null) {
            if ($this->throwsExceptions) {
                throw new SDKError();
            }

            return [(string) $response->getBody()];
        }

        if (($json['status'] === false) && ($this->throwsExceptions)) {
            throw new SDKException(
                $json['error']['message'],
                $json['error']['type'],
                $json['error']['link']
            );
        }

        return $json;
    }