/**
* @name isNull
* @summary Tests for a `null` values.
* @description
* Checks to see if the input value is `null`.
* @example
* <BR>
*
* ```javascript
* import { isNull } from '@polkadot/util';
*
* console.log('isNull', isNull(null)); // => true
* ```
*/
export declare function isNull(value?: unknown): value is null;