export declare function isFunction(val: unknown): val is Function; export declare function isPlainObject( val: unknown ): val is Record; export declare function isPromise(val: unknown): val is Promise; export declare function isDef(value: unknown): boolean; export declare function isObj(x: unknown): x is Record; export declare function isNumber(value: string): boolean; export declare function isBoolean(value: unknown): value is boolean; export declare function isImageUrl(url: string): boolean; export declare function isVideoUrl(url: string): boolean;