/**
 * uses {@link Number.isNaN} under the hood
 * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN
 * @todo exclude `NaN` value as soon as {@link https://github.com/microsoft/TypeScript/issues/28682} gets resolved
 * @returns `true` when value is `NaN`
 */
export declare const isNaN: (_: unknown) => _ is number;