WooCommerce Mollie - Add currencies to the payment plugin

/**
 * Mollie gateway for WooCommerce. Adds extra currencies to the "supported
 * currencies" list used by the Mollie payment plugin.
 *
 * HOW TO USE THIS CODE
 * Simply add the code to the bottom of your theme's functions.php file, and it
 * will run automatically. For more information: https://www.skyverge.com/blog/add-custom-code-to-wordpress/
 *
 * GPL DISCLAIMER
 * Because this code program is free of charge, there is no warranty for it, to the extent permitted by applicable law.
 * Except when otherwise stated in writing the copyright holders and/or other parties provide the program "as is"
 * without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of
 * merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the program
 * is with you. should the program prove defective, you assume the cost of all necessary servicing, repair or correction.
 *
 * Need a consultation, or assistance to customise this code? Find us on Codeable: https://aelia.co/hire_us
 */

/**
 * Adds currencies to the list of currencies supported by Mollie.
 * IMPORTANT: this will prevent the Mollie gateway from disabling itself when an
 * unsupported currency is detecte, but it won't allow Mollie to accept
 * payments in the added currencies
 *
 * @param array currencies
 * @return array
 */
function aelia_add_mollie_currencies($currencies) {
  // Add USD to the currencies supported by Mollie.
  $currencies[] = 'USD';
  return $currencies;
}

/**
 * Classes used by Mollie gateway. The class, in lower-case is also the ID of
 * the gateway.
 */
$aelia_mollie_classes = array(
  'Mollie_WC_Gateway_BankTransfer',
  'Mollie_WC_Gateway_BelfiusSepaRecurring',
  'Mollie_WC_Gateway_Bitcoin',
  'Mollie_WC_Gateway_CreditcardSubscription',
  'Mollie_WC_Gateway_DirectDebit',
  'Mollie_WC_Gateway_Giftcard',
  'Mollie_WC_Gateway_IdealSepaRecurring',
  'Mollie_WC_Gateway_Kbc',
  'Mollie_WC_Gateway_MisterCashSepaRecurring',
  'Mollie_WC_Gateway_PayPal',
  'Mollie_WC_Gateway_Paysafecard',
  'Mollie_WC_Gateway_SofortSepaRecurring',
);

// Add a filter for each of the Mollie gateways, to alter the list of supported
// currencies
foreach($aelia_mollie_classes as $mollie_class) {
  $mollie_class = strtolower($mollie_class);
  add_filter("woocommerce_{$mollie_class}_supported_currencies", 'aelia_add_mollie_currencies');
}