^^&&^^

Edit File: ParentNodeDefinitionInterface.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\Definition\Builder;

/**
 * An interface that must be implemented by nodes which can have children.
 *
 * @author Victor Berchet <victor@suumit.com>
 *
 * @method NodeDefinition[] getChildNodeDefinitions() Gets the child node definitions - not implementing it is deprecated since Symfony 4.2
 */
interface ParentNodeDefinitionInterface extends BuilderAwareInterface
{
    /**
     * Returns a builder to add children nodes.
     *
     * @return NodeBuilder
     */
    public function children();

/**
     * Appends a node definition.
     *
     * Usage:
     *
     *     $node = $parentNode
     *         ->children()
     *             ->scalarNode('foo')->end()
     *             ->scalarNode('baz')->end()
     *             ->append($this->getBarNodeDefinition())
     *         ->end()
     *     ;
     *
     * @return $this
     */
    public function append(NodeDefinition $node);
}