declare global {
    interface Set<T> {
        toReadonly(): ReadonlySet<T>;
    }
}
export declare class RuntimeReadonlySet<T> implements ReadonlySet<T> {
    private readonly _wrap;
    constructor(_wrap: Set<T>);
    forEach(callbackfn: (value: T, value2: T, set: ReadonlySet<T>) => void, thisArg?: any): void;
    has(value: T): boolean;
    get size(): number;
    entries(): SetIterator<[T, T]>;
    keys(): SetIterator<T>;
    values(): SetIterator<T>;
    [Symbol.iterator](): SetIterator<T>;
}