public function rm($key)
    {
        try {
            $response = $this->guzzleclient->delete($this->buildKeyUri($key));
        } catch (BadResponseException $e) {
            $response = $e->getResponse();
        }
        $body = json_decode($response->getBody(), true);
        if (JSON_ERROR_NONE !== json_last_error()) {
            throw new RuntimeException('Unable to parse response body into JSON: ' . json_last_error());
        }

        if (isset($body['errorCode'])) {
            throw new EtcdException($body['message'], $body['errorCode']);
        }

        return $body;
    }