export declare function getId(): string;
export declare function walkTree<T>(tree: T, callback: (item: T, next: () => void, parent?: T) => void, key?: string): void;
export declare function arrayFrom<T>(arrayLike: ArrayLike<T>): T[];
export declare function flatMap<T, U>(arrayLike: ArrayLike<T>, callback: (item?: T, index?: number, thisObj?: ArrayLike<T>) => U | U[]): U[];
export declare function addClass(className: string, ...rest: string[]): string;
export declare function childSelector<T extends Element>(filter?: string | ((el: T) => boolean)): () => T[];