public function getPaymentCurrencyOptions()
    { 
        // Create the base options
        $options = [
            [
                'value' => self::BASE_CURRENCY,
                'label' => __('Use Magento default')
            ],
            [
                'value' => self::ORDER_CURRENCY,
                'label' => __('Order currency')
            ],
            [
                'value' => self::CUSTOM_CURRENCY,
                'label' => __('Custom currency')
            ],
        ];

        // Return the options as array
        return $options;
    }