/**
 * #### Generates a unique id
 *
 * Starts a new counter for every unique prefix and if a prefix is given, returns the id by prefixing it, otherwise returns the id as number
 * * * *
 * Example usage:
 * ```typescript
 * import { uniqueId } from "@thalesrc/js-utils";
 *
 * uniqueId(); // 0
 * uniqueId(); // 1
 * uniqueId("some-str"); // "some-str-0";
 * uniqueId("some-str"); // "some-str-1";
 * uniqueId(); // 3
 * ```
 * * * *
 * @param prefix prefix to prepend into the unique id
 * @returns A unique id
 */
export declare function uniqueId(): number;
export declare function uniqueId(prefix: string): string;