protected function addUris(array $tracks, int $position = null)
    {
        if ($position === null) {
            $position = $this->getNextPosition();
        }

        foreach ($tracks as $track) {
            $data = $this->soap("AVTransport", "AddURIToSavedQueue", [
                "UpdateID"              =>  $this->updateId,
                "EnqueuedURI"           =>  $track->getUri(),
                "EnqueuedURIMetaData"   =>  $track->getMetaData(),
                "AddAtIndex"            =>  $position,
            ]);
            $this->updateId = $data["NewUpdateID"];

            $position++;
        }
    }