export declare class DiffUtil {
    /**
     * Deeply flattens an array or set of elements.
     *
     * @template T
     * @param {T[] | Set<T>} data - The data to flatten.
     * @returns {T[]} A flattened array of elements.
     */
    static deepFlat<T>(data: T[] | Set<T>): T[];
    /**
     * Flattens a nested array or set of virtual nodes (VNode) and adds the result to the `containerArr`.
     *
     * @template T
     * @param {(T | T[])[] | Set<T | T[]>} arr - The array or set of VNode children to flatten.
     * @param {T[]} [containerArr=[]] - The container array to store flattened nodes.
     * @returns {T[]} The flattened array of VNode children.
     */
    static flattenVNodeChildren<T>(arr: (T | T[])[] | Set<T | T[]>, containerArr?: T[]): T[];
}