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