/**
 * Converts a date to a string according to the specified format pattern.
 * @param {Date} date - The date object to format
 * @param {string} formatString - The format pattern string (default: "YYYY-MM-DDTHH:mm:ssZ")
 * @return {string} - The formatted date string
 * @example
 * format(new Date('2025-04-04'), 'YYYY-MM-DD') // Returns "2025-04-04"
 * format(new Date('2025-04-04T15:30:00'), 'HH:mm') // Returns "15:30"
 * format(new Date('2025-04-04'), 'MM/DD/YYYY') // Returns "04/04/2025"
 *
 * Available format tokens:
 * - YYYY: Full year (e.g., 2025)
 * - YY: Short year (e.g., 25)
 * - MM: Month with leading zero (01-12)
 * - M: Month without leading zero (1-12)
 * - DD: Day with leading zero (01-31)
 * - D: Day without leading zero (1-31)
 * - d: Day of week (0-6)
 * - HH: Hours with leading zero (00-23)
 * - H: Hours without leading zero (0-23)
 * - hh: Hours (12-hour) with leading zero (01-12)
 * - h: Hours (12-hour) without leading zero (1-12)
 * - mm: Minutes with leading zero (00-59)
 * - m: Minutes without leading zero (0-59)
 * - ss: Seconds with leading zero (00-59)
 * - s: Seconds without leading zero (0-59)
 * - SSS: Milliseconds with leading zeros (000-999)
 * - A: AM/PM
 * - a: am/pm
 * - Z: Timezone offset (+09:00)
 * - ZZ: Timezone offset without colon (+0900)
 */
export declare const format: (date: Date, formatString?: string) => string;