import type { AnyCaller } from "./function.js";
/** Function that always returns undefined. */
export declare function getUndefined(): undefined;
/** Is a value undefined? */
export declare function isUndefined(value: unknown): value is undefined;
/** Is a value defined? */
export declare function isDefined<T>(value: T | undefined): value is T;
/** Is a value defined? */
export declare const notUndefined: typeof isDefined;
/** Assert that a value is not `undefined` */
export declare function assertDefined<T>(value: T | undefined, caller?: AnyCaller): asserts value is T;
/** Get a defined value. */
export declare function requireDefined<T>(value: T | undefined, caller?: AnyCaller): T;