export declare function isObjectLiteral(item: unknown): boolean;
export declare function attachInternals(element: HTMLElement & {
    _internals?: ElementInternals;
}): ElementInternals;
export declare function toggleState(internals: ElementInternals, state: string, force: boolean): void;
export type PopoverAnchorElement = HTMLElement & {
    anchor?: HTMLElement | string;
    _activeTrigger?: HTMLElement;
};
export declare function getFlattenedDOMTree(node: Node, depth?: number): HTMLElement[];
export declare function getHostAnchor(host: PopoverAnchorElement): HTMLElement;
export declare function getStringValue(value: unknown): string | null;
export declare function hasAttributeValue(element: HTMLElement, attribute: string, value: string | null): boolean;
export declare function isFormElement(value: unknown): value is HTMLFormElement;
export declare function onKeys(events: string[], event: KeyboardEvent, callback: () => void): void;
export declare function removeEmptyTextNode(node: Node): void;
export declare function setAttributeValue(element: HTMLElement, attribute: string, value: string | null): void;
export declare function stopEvent(event: Event): void;