import { ValidationException } from './ValidationException';
/**
 * Is the value undefined?
 * See: https://developer.mozilla.org/en-US/docs/Glossary/undefined
 *
 * @example
 * ```ts
 * isUndefined(undefined) // true
 * isUndefined(1) // false
 * ```
 *
 * @param value the value to check
 * @returns a boolean indicating whether the value is the expected type
 */
export declare const isUndefined: (value: unknown) => value is undefined;
/**
 * Validate that the value is undefined.
 * See: https://developer.mozilla.org/en-US/docs/Glossary/undefined
 *
 * @example
 * ```ts
 * validateUndefined(undefined) // null
 * validateUndefined(1) // ValidationException
 * ```
 *
 * @param value the value to check
 * @returns `null` if the value is the expected type or a `ValidationException`
 * if not
 */
export declare const validateUndefined: (value: unknown) => ValidationException | null;
/**
 * Assert that the value is undefined.
 * See: https://developer.mozilla.org/en-US/docs/Glossary/undefined
 *
 * @example
 * ```ts
 * assertUndefined(undefined) // void
 * assertUndefined(1) // throws AssertionException
 * ```
 *
 * @param value the value to check
 * @throws an `AssertionException` if the value is not the expected type
 */
export declare const assertUndefined: (value: unknown) => asserts value is undefined;