export const COUNTDOWN_STATE: Readonly<{
    READY: "READY";
    RUNNING: "RUNNING";
    STOPPED: "STOPPED";
}>;
export default useCountDown;
declare function useCountDown({ startTime, onCountDownDone }: {
    startTime?: number | undefined;
    onCountDownDone: any;
}): {
    state: "READY";
    countdown: number;
    startCountDown: () => void;
    stopCountDown: () => void;
};