export interface IAttributeMap {
    [key: string]: string | null;
}
export declare function compose(a: IAttributeMap | undefined, b: IAttributeMap | undefined, keepNull: boolean): IAttributeMap | undefined;
export declare function diff(a?: IAttributeMap, b?: IAttributeMap): IAttributeMap | undefined;
export declare function invert(attr?: IAttributeMap, base?: IAttributeMap): IAttributeMap;
export declare function transform(a: IAttributeMap | undefined, b: IAttributeMap | undefined, priority?: boolean): IAttributeMap | undefined;