declare type MaybePromise<T> = T | Promise<T>;
/**
 * Basic interface required to manage tokens for the `Client`. The client handles parallelism, these
 * are simple functions that manipulate some kind of persistent storage.
 */
export interface AsyncStorage {
    getItem(key: string): MaybePromise<string | null>;
    setItem(key: string, value: string): MaybePromise<void>;
    removeItem(key: string): MaybePromise<void>;
}
export declare function createInMemoryStorage(): AsyncStorage;
export {};