import { ValidationException } from './ValidationException';
/**
 * Is the value null or undefined?
 *
 * @example
 * ```ts
 * isNil(null) // true
 * isNil(undefined) // true
 * isNil(1) // false
 * ```
 *
 * @param value the value to check
 * @returns a boolean indicating whether the value is the expected type
 */
export declare const isNil: (value: unknown) => value is null | undefined;
/**
 * Validate that the value is null or undefined.
 *
 * @example
 * ```ts
 * validateNil(null) // null
 * validateNil(undefined) // null
 * validateNil(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 validateNil: (value: unknown) => ValidationException | null;
/**
 * Assert that the value is null or undefined.
 *
 * @example
 * ```ts
 * assertNil(null) // void
 * assertNil(undefined) // void
 * assertNil(1) // throws AssertionException
 * ```
 *
 * @param value the value to check
 * @throws an `AssertionException` if the value is not the expected type
 */
export declare const assertNil: (value: unknown) => asserts value is null | undefined;