export declare const hasKeys: <T>(v: T) => v is T extends undefined ? never : T;
export declare const isArray: (val: any) => val is any[];
export declare const isSysError: (error: any) => error is Error;
export declare const isFunc: (func: any) => boolean;
export declare const isNumber: (val: any) => val is number;
export declare const isNull: (val: any) => val is null;
export declare const isUndefined: (val: any) => val is undefined;
export declare const isNullOrUndefined: (val: any) => val is null | undefined;
export declare const isObject: <S>(val: S) => val is Exclude<S, string | number | boolean | null | undefined>;
export declare const isString: (val: any) => val is string;
export declare const isStringArray: (val: any) => val is string[];