export declare type KeyType = string | number | symbol;
export declare const isString: (val: unknown) => val is string;
export declare const isBool: (val: unknown) => val is boolean;
export declare const isNumber: (val: unknown) => val is number;
export declare const isObject: <T extends KeyType, U = any>(val: unknown) => val is Record<T, U>;
export declare const isNil: (val: unknown) => boolean;