export type BarrierAction<T> = {
    ready: (val: T) => Promise<T>;
    remove: () => void;
};
/**
 * A class to help make async code execute at the same time.
 *
 * Making sure all participants are ready before continuing.
 */
export default class Barrier<T> {
    private listeners;
    private lastValue;
    private open;
    constructor();
    /**
     * Returns true if the barrier is already opened meaning the add
     * function would panic
     */
    isOpen(): boolean;
    /**
     * Add yourself to the barrier
     *
     * Only if all participants call ready the barrier is opened.
     *
     * @throws if the barrier is already open
     */
    add(): BarrierAction<T>;
    private _maybeTrigger;
}
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