public function getAllOpenReturns($from, $to = '', array $options = []) {
        if (empty($to)) {
            $to = date('YmdHs');
        }
        $query_params = "from={$from}&to{$to}";

        $this->verifyDates($from, $to);

        $response = $this->get(
            "rs/{$this->config['customer_number']}/{$this->config['customer_number']}/openreturn?{$query_params}",
            [
                'Accept' => 'application/vnd.cpc.openreturn+xml',
                'Content-Type' => 'application/vnd.cpc.openreturn+xml',
            ],
            $options
        );
        return $response;

    }