/**
 * Returns function that yields current mount state.
 *
 * Returned function yields `true` only in case component is mounted. This hook
 * is handy for the cases when you have to detect component mount state within
 * async effects.
 *
 * @param initialValue Initial value. By default, this hook assumes that hook is
 * not mounted yet at first render.
 */
export declare function useIsMounted(initialValue?: boolean): () => boolean;