import { BaseError } from 'make-error';
import { Constrained } from '../../core';
export declare class InvalidISO8601DurationError extends BaseError {
    constructor();
}
export declare const iso8601DurationSymbol: unique symbol;
export type ISO8601Duration = Constrained<typeof iso8601DurationSymbol, string>;
export declare function isISO8601Duration(input: unknown): input is ISO8601Duration;
export declare function iso8601Duration(input: unknown): ISO8601Duration;