import type { DateTime, DateTimeInput, FormatInput, TimeZone } from '../typings';
/**
 * Checks if value is DateTime.
 * @param {unknown} value - value to check.
 */
export declare function isDateTime(value: unknown): value is DateTime;
/**
 * Creates a DateTime instance.
 * @param opt
 * @param {DateTimeInput=} opt.input - input to parse.
 * @param {string=} opt.format - strict {@link https://dayjs.gitee.io/docs/en/display/format format} for parsing user's input.
 * @param {string=} opt.timeZone - specified {@link https://dayjs.gitee.io/docs/en/timezone/timezone time zone}.
 * @param {string=} opt.lang - specified locale.
 */
export declare function dateTime(opt?: {
    input?: DateTimeInput;
    format?: FormatInput;
    timeZone?: TimeZone;
    lang?: string;
}): DateTime;
/**
 * Creates a DateTime instance with fixed offset.
 * @param [opt]
 * @param {DateTimeInput=} [opt.input] - input to parse.
 * @param {string=} [opt.format] - strict {@link https://dayjs.gitee.io/docs/en/display/format format} for parsing user's input.
 * @param {number=} [opt.offset] - specified offset.
 * @param {string=} [opt.lang] - specified locale.
 */
export declare function dateTimeUtc(opt?: {
    input?: DateTimeInput;
    format?: FormatInput;
    lang?: string;
    offset?: number;
}): DateTime;