/**
 * @name addQuarters
 * @category Quarter Helpers
 * @summary Add the specified number of year quarters to the given date.
 *
 * @description
 * Add the specified number of year quarters to the given date.
 *
 * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
 *
 * @param date - The date to be changed
 * @param amount - The amount of quarters to be added.
 *
 * @returns The new date with the quarters added
 *
 * @example
 * // Add 1 quarter to 1 September 2014:
 * const result = addQuarters(new Date(2014, 8, 1), 1)
 * //=> Mon Dec 01 2014 00:00:00
 */
export declare function addQuarters<DateType extends Date>(
  date: DateType | number | string,
  amount: number,
): DateType;
