/**
 * @internal
 *
 * If you need access to the first focusable descendant of a container, you can use
 * `getFirstFocusableChild`. The function uses the
 * https://developer.mozilla.org/en-US/docs/Web/API/TreeWalker to
 * iterate over the children of the container and returns either a `Node` if a
 * focusable element is found, or `null`.
 */
export declare function getFirstFocusableChild(container: HTMLElement | Node): Node | null;