/**
* Utilities for caching results of function invocations (a.k.a. memoization).
*
* @public
* @module lang/memoize
*/
/**
 * Memoizes a function that accepts a single argument only. Furthermore,
 * the parameter's toString function must return a unique value.
 *
 * @static
 * @public
 * @param {Function} fn - The function to memoize. This function should accept one parameter whose "toString" function outputs a unique value.
 */
export function simple(fn: Function): (x: any) => any;
/**
 * Wraps a function. The resulting function will call the wrapped function
 * once and cache the result. If a specific duration is supplied, the
 * cache will be dropped after the duration expires and the wrapped
 * function will be invoked again.
 *
 * @public
 * @param {Function} fn
 * @param {number} duration
 * @returns {Function}
 */
export function cache(fn: Function, duration: number): Function;