/**
 * Generate a unique identifier with an optional prefix.
 * @param prefix - Optional prefix for the ID.
 * @returns A unique identifier string.
 */
export declare function generateUniqueId(prefix?: string): string;
/**
 * Adds or removes a state from an element's custom state set.
 *
 * @param internals - The element's internals object.
 * @param state - The name of the custom state to toggle.
 * @param value - Whether to add or remove the state.
 */
export declare function toggleState(internals: ElementInternals, state: string, value: boolean): void;