/**
 * Accepts a parameter and returns it if it's a function
 * or a noop function if it's not. This allows us to
 * accept a callback, but not worry about it if it's not
 * passed.
 * @param {Function} cb the callback
 * @return {Function} a function
 */
export function cbToCb(cb: Function): Function;
/**
 * Default implementation for status message. Only added when menu is open.
 * Will specify if there are results in the list, and if so, how many,
 * and what keys are relevant.
 *
 * @param {Object} param the downshift state and other relevant properties
 * @return {String} the a11y status message
 */
export function getA11yStatusMessage({ isOpen, resultCount, previousResultCount }: Object): string;
/**
 * Takes an argument and if it's an array, returns the first item in the array
 * otherwise returns the argument
 * @param {*} arg the maybe-array
 * @param {*} defaultValue the value if arg is falsey not defined
 * @return {*} the arg or it's first item
 */
export function unwrapArray(arg: any, defaultValue: any): any;
/**
 * @param {Object} element (P)react element
 * @return {Boolean} whether it's a DOM element
 */
export function isDOMElement(element: Object): boolean;
/**
 * @param {Object} element (P)react element
 * @return {Object} the props
 */
export function getElementProps(element: Object): Object;
/**
 * Throws a helpful error message for required properties. Useful
 * to be used as a default in destructuring or object params.
 * @param {String} fnName the function name
 * @param {String} propName the prop name
 */
export function requiredProp(fnName: string, propName: string): void;
/**
 * @param {Object} state the state object
 * @return {Object} state that is relevant to downshift
 */
export function pickState(state?: Object): Object;
/**
 * Simple check if the value passed is object literal
 * @param {*} obj any things
 * @return {Boolean} whether it's object literal
 */
export function isPlainObject(obj: any): boolean;