export default class Storage {
    /**
     * Gets the value at `key`. Returns a promise that will be resolved
     * with that value (or undefined for missing keys).
     */
    get(key: string): Promise<any>;
    /**
     * Sets the `value` on `key` and returns a promise that will be resolved
     * with the value that was set.
     */
    set(key: string, value: any): Promise<any>;
    /**
     * Deletes the value at `key`. Returns a promise that will be resolved
     * with true if the key was deleted or with false if it was not (eg. if
     * did not exist).
     */
    unset(key: string): Promise<boolean>;
}