How to use the @paypal/sdk-constants/src.SDK_QUERY_KEYS.CURRENCY function in @paypal/sdk-constants

]).then(([ gql, payee ]) => {

        const cart = gql.checkoutSession.cart;

        const intent = (cart.intent.toLowerCase() === 'sale') ? INTENT.CAPTURE : cart.intent.toLowerCase();
        const currency = cart.amounts && cart.amounts.total.currencyCode;

        const expectedIntent = intent;
        const expectedCurrency = currency;

        if (intent !== expectedIntent) {
            throw new Error(`Expected intent from order api call to be ${ expectedIntent }, got ${ intent }. Please ensure you are passing ${ SDK_QUERY_KEYS.INTENT }=${ intent } to the sdk`);
        }

        if (currency && currency !== expectedCurrency) {
            throw new Error(`Expected currency from order api call to be ${ expectedCurrency }, got ${ currency }. Please ensure you are passing ${ SDK_QUERY_KEYS.CURRENCY }=${ currency } to the sdk`);
        }

        const payeeMerchantID = payee && payee.merchant && payee.merchant.id;
        const actualMerchantID = merchantID && merchantID.length && merchantID[0];

        if (!actualMerchantID) {
            throw new Error(`Could not determine correct merchant id`);
        }

        if (!payeeMerchantID) {
            throw new Error(`No payee found in transaction. Expected ${ actualMerchantID }`);
        }

        if (payeeMerchantID !== actualMerchantID) {
            if (clientID && CLIENT_ID_PAYEE_NO_MATCH.indexOf(clientID) === -1) {
                getLogger().info(`client_id_payee_no_match_${ clientID }`).flush();

export function getCurrency() : $Values {
    return getSDKQueryParam(SDK_QUERY_KEYS.CURRENCY, DEFAULT_CURRENCY);
}

order.purchase_units = order.purchase_units.map(unit => {
        if (unit.amount.currency_code && unit.amount.currency_code !== currency) {
            throw new Error(`Unexpected currency: ${ unit.amount.currency_code } passed to order.create. Please ensure you are passing /sdk/js?${ SDK_QUERY_KEYS.CURRENCY }=${ unit.amount.currency_code } in the paypal script tag.`);
        }

        let payee = unit.payee;

        if (payee) {
            if (!merchantID) {
                throw new Error(`Pass ${ SDK_QUERY_KEYS.MERCHANT_ID }=XYZ in the paypal script tag. Pass ${ SDK_QUERY_KEYS.MERCHANT_ID }=${ UNKNOWN } if you do not have access to the merchant id`);
            }

            if (payee.merchant_id && merchantID[0] !== UNKNOWN && payee.merchant_id !== merchantID) {
                throw new Error(`Expected payee.merchant_id to be "${ merchantID[0] }"`);
            }
        }
        
        if (merchantID && merchantID[0] !== UNKNOWN) {
            payee = {

const cart = res.data.checkoutSession.cart;

        const intent = (cart.intent.toLowerCase() === 'sale') ? INTENT.CAPTURE : cart.intent.toLowerCase();
        const currency = cart.amounts && cart.amounts.total.currencyCode;
        const returnUrl = cart.returnUrl && cart.returnUrl.href;
        const cancelUrl = cart.cancelUrl && cart.cancelUrl.href;

        const expectedIntent = window.xprops.intent;
        const expectedCurrency = window.xprops.currency;

        if (intent !== expectedIntent) {
            throw new Error(`Expected intent from order api call to be ${ expectedIntent }, got ${ intent }. Please ensure you are passing ${ SDK_QUERY_KEYS.INTENT }=${ intent } to the sdk`);
        }

        if (currency && currency !== expectedCurrency) {
            throw new Error(`Expected currency from order api call to be ${ expectedCurrency }, got ${ currency }. Please ensure you are passing ${ SDK_QUERY_KEYS.CURRENCY }=${ currency } to the sdk`);
        }

        if (isOrderID(orderID)) {
            if (returnUrl && returnUrl.indexOf(ERROR_URL) !== 0) {
                throw new Error(`Return url is forbidden for smart payment button integration.`);
            }

            if (cancelUrl && cancelUrl.indexOf(ERROR_URL) !== 0) {
                throw new Error(`Cancel url is forbidden for smart payment button integration.`);
            }
        }
    });
}

order.purchase_units = order.purchase_units.map(unit => {
            if (unit.amount.currency_code && unit.amount.currency_code !== currency) {
                throw new Error(`Unexpected currency: ${ unit.amount.currency_code } passed to order.create. Please ensure you are passing /sdk/js?${ SDK_QUERY_KEYS.CURRENCY }=${ unit.amount.currency_code } in the paypal script tag.`);
            }

            let payee = unit.payee;
    
            if (payee && merchantID && merchantID.length) {
                if (!merchantID[0]) {
                    throw new Error(`Pass ${ SDK_QUERY_KEYS.MERCHANT_ID }=XYZ in the paypal script tag.`);
                }
    
                if (payee.merchant_id && payee.merchant_id !== merchantID[0]) {
                    throw new Error(`Expected payee.merchant_id to be "${ merchantID[0] }"`);
                }
            }
    
            if (merchantID) {
                payee = {