export declare function setFirstValue<K>(set: Set<K>): K | undefined;
export declare function setToArray<T>(set: Set<T>, target: T[]): T[];
export declare function setCopy<T>(src: Set<T>, target: Set<T>): Set<T>;
export declare function setUnion<T extends string | number>(set0: Set<T>, set1: Set<T>, target: Set<T>): Set<T>;
export declare function setIntersection<T extends string | number>(set0: Set<T>, set1: Set<T>, target: Set<T>): Set<T>;
export declare function setDifference<T extends string | number>(set0: Set<T>, set1: Set<T>, target: Set<T>): Set<T>;
export declare function setXOR<T extends string | number>(set0: Set<T>, set1: Set<T>, target: Set<T>): Set<T>;