/**
 * Groups array into object composed by keys
 * @param array source of array
 * @param prop object key or function that returns a value
 * @example
 * groupBy([{ b: 1 }], 'b')
 * groupBy([{ b: 1.23 }], (e) => e.toFixed())
 */
export declare function groupBy(array: any[], prop: string | any): {
    [key: string]: any[];
};