^^&&^^

Edit File: ResourceInterface.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Config\Resource;

/**
 * ResourceInterface is the interface that must be implemented by all Resource classes.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
interface ResourceInterface
{
    /**
     * Returns a string representation of the Resource.
     *
     * This method is necessary to allow for resource de-duplication, for example by means
     * of array_unique(). The string returned need not have a particular meaning, but has
     * to be identical for different ResourceInterface instances referring to the same
     * resource; and it should be unlikely to collide with that of other, unrelated
     * resource instances.
     *
     * @return string A string representation unique to the underlying Resource
     */
    public function __toString();
}