export interface ListMap<T> {
    [x: string]: T[];
}
export interface Map<T> {
    [x: string]: T;
}
export declare function aggregateBy<T>(data: Array<T>, fn: (T: any) => string): ListMap<T>;
export declare function aggregateFlatBy<T>(data: Array<T>, fn: (T: any) => string): Map<T>;