export declare function isString(str: any): str is string;
export declare function isUndefined(obj: any): obj is undefined;
export declare function isArray(obj: unknown): obj is any[];
export declare function isFunction(func: any): func is Function;
export declare function isObject(obj: unknown): obj is Record<string, any>;
export declare function isPlainObject(obj: unknown): obj is Record<string, any>;
export declare function isPromise(obj: any): obj is Promise<any>;
export declare function isRegExp(obj: any): obj is RegExp;
/**
 * Is Empty object
 *
 * @param o - Any object.
 * @returns Whether it is empty object.
 */
export declare const isEmpty: (o: Record<string, unknown>) => boolean;