/**
 * @license
 * Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at
 * http://polymer.github.io/LICENSE.txt The complete set of authors may be found
 * at http://polymer.github.io/AUTHORS.txt The complete set of contributors may
 * be found at http://polymer.github.io/CONTRIBUTORS.txt Code distributed by
 * Google as part of the polymer project is also subject to an additional IP
 * rights grant found at http://polymer.github.io/PATENTS.txt
 */
export declare function isValidCustomElementName(localName: string): boolean;
export declare function isConnected(node: Node): boolean;
export declare function childrenFromFragment(fragment: DocumentFragment): Array<Element>;
export declare function walkDeepDescendantElements(root: Node, callback: (elem: Element) => void, visitedImports?: Set<Node>): void;