import { CallBack } from "./typedefs";
export declare class PromiseChainLock {
    private queue;
    /**
     * An async function that waits to acquire the lock, then provides a function to unlock.
     * Use like:
     * const unlockingFunction = await promiseChainLock.acquireLock();
     * try {
     *   // Do some stuff.
     * } finally {
     *   unlockingFunction();
     * }
     * @returns a promise that resolves when the lock has been acquired, resolving to a cb to unlock it.
     */
    acquireLock(): Promise<CallBack>;
}