newsupernova/vendor/magento/module-currency-symbol/Controller/Adminhtml/System/Currency.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

/**
 * Currency controller
 *
 * @author      Magento Core Team <core@magentocommerce.com>
 */
namespace Magento\CurrencySymbol\Controller\Adminhtml\System;

/**
 * @api
 * @since 100.0.2
 */
abstract class Currency extends \Magento\Backend\App\Action
{
    /**
     * Authorization level of a basic admin session
     *
     * @see _isAllowed()
     */
    const ADMIN_RESOURCE = 'Magento_CurrencySymbol::currency_rates';

    /**
     * Core registry
     *
     * @var \Magento\Framework\Registry
     */
    protected $_coreRegistry = null;

    /**
     * @param \Magento\Backend\App\Action\Context $context
     * @param \Magento\Framework\Registry $coreRegistry
     */
    public function __construct(\Magento\Backend\App\Action\Context $context, \Magento\Framework\Registry $coreRegistry)
    {
        $this->_coreRegistry = $coreRegistry;
        parent::__construct($context);
    }
}