import type { Extended } from './isExtension.js';
export declare const $SET: unique symbol;
export type $SET = typeof $SET;
export declare const $set: <VALUE>(value: VALUE) => SET<VALUE>;
export declare const isSetting: (input: unknown) => input is {
    [$SET]: unknown;
};
export type SET<VALUE> = Extended<{
    [$SET]: VALUE;
}>;