export declare class Set<T> {
    collection: Array<T>;
    constructor(collection?: Array<T>);
    has(element: T): boolean;
    readonly values: Array<T>;
    add(element: T): boolean;
    remove(element: T): boolean;
    readonly size: number;
    union(otherSet: Set<T>): Set<unknown>;
    intersection(otherSet: Set<T>): Set<unknown>;
    difference(otherSet: Set<T>): Set<unknown>;
    subset(otherSet: Set<T>): boolean;
}