/**
 * @title isEmpty
 * @description 是无效值 undefined , null, NaN
 * @param value {unknown} 待值
 * @returns boolean
 */
export declare function isEmpty(value: unknown): value is (undefined | null);
/**
 * @title isNoEmpty
 * @description 不是是无效值 undefined , null, NaN
 * @param value {unknown}
 * @returns boolean
 * @version 0.3.0
 */
export declare function isNoEmpty(value: unknown): value is (undefined | null);
/**
 * @title isNull
 * @param value {unknown}
 * @returns boolean
 */
export declare function isNull(value: unknown): value is null;
/**
 * @title isUndefined
 * @param value {unknown}
 * @returns boolean
 */
export declare function isUndefined(value: unknown): value is undefined;
/**
 * @title isNaN
 * @param value {unknown}
 * @returns boolean
 */
export declare const isNaN: (number: unknown) => boolean;
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