/**
 * Return a copy of the set, with the item excluded.
 */
export declare function excluding<T>(set: ReadonlySet<T>, item: T): ReadonlySet<T>;
export declare const empty: ReadonlySet<never>;
/**
 * Return a copy of the set, with the item included.
 */
export declare function including<T>(set: ReadonlySet<T>, item: T): ReadonlySet<T>;
/**
 * Return a copy of the set, with the item removed it is was present, else with
 * it added.
 */
export declare function toggled<T>(set: ReadonlySet<T>, item: T): ReadonlySet<T>;
/**
 * Return the items in the set as an array.
 */
export declare function toArray<T>(set: ReadonlySet<T>): T[];
/**
 * Combine the items from two sets.
 */
export declare function union<T>(a: ReadonlySet<T>, b: ReadonlySet<T>): ReadonlySet<T>;
export declare function subtraction<T>(a: ReadonlySet<T>, b: ReadonlySet<T>): ReadonlySet<T>;
export declare function intersection<T>(a: ReadonlySet<T>, b: ReadonlySet<T>): ReadonlySet<T>;
export declare function some<T>(a: ReadonlySet<T>, predicate: (item: T) => boolean): boolean;
export declare class CountedSet<T> {
    private readonly counts;
    constructor(counts?: Map<T, number>);
    add(item: T): number;
    remove(item: T): number;
    count(item: T): number;
    filter(predicate: (item: T, count: number) => boolean): IterableIterator<T>;
    entries(): IterableIterator<[T, number]>;
    copy(): CountedSet<T>;
}