export declare const isDefined: <T>(value: T | null | undefined) => value is T;
export declare const isString: (value: unknown) => value is string;
export declare const isNumber: (value: unknown, exact?: boolean) => value is number;
export declare const isObject: (value: any) => boolean;
export declare const isBrowser: () => boolean;
export declare const isValidDate: (value: any) => boolean;