https://developer.intuit.com/app/developer/qbo/docs/develop/sdks-and-samples-collections/php/synchronous-calls#batch-process

The following example code from the above link is incorrect:
$batch->AddQuery("select * from Customer startPosition 0 maxResults 20", "queryCustomer", "uniqueQuery");

AddQuery takes 2 parameters:

    /**
     * Adds the specified query.
     * @param string $query IDS query.
     * @param string $id unique batchitem id.
     */
    public function AddQuery($query, $id)