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+import getISOWeekYear from '../getISOWeekYear/index'
+import requiredArgs from '../_lib/requiredArgs/index'
+
+/**
+ * @name differenceInCalendarISOWeekYears
+ * @category ISO Week-Numbering Year Helpers
+ * @summary Get the number of calendar ISO week-numbering years between the given dates.
+ *
+ * @description
+ * Get the number of calendar ISO week-numbering years between the given dates.
+ *
+ * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
+ *
+ * ### v2.0.0 breaking changes:
+ *
+ * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
+ *
+ * - The function was renamed from `differenceInCalendarISOYears` to `differenceInCalendarISOWeekYears`.
+ *   "ISO week year" is short for [ISO week-numbering year](https://en.wikipedia.org/wiki/ISO_week_date).
+ *   This change makes the name consistent with
+ *   locale-dependent week-numbering year helpers, e.g., `addWeekYears`.
+ *
+ * @param {Date|Number} dateLeft - the later date
+ * @param {Date|Number} dateRight - the earlier date
+ * @returns {Number} the number of calendar ISO week-numbering years
+ * @throws {TypeError} 2 arguments required
+ *
+ * @example
+ * // How many calendar ISO week-numbering years are 1 January 2010 and 1 January 2012?
+ * const result = differenceInCalendarISOWeekYears(
+ *   new Date(2012, 0, 1),
+ *   new Date(2010, 0, 1)
+ * )
+ * //=> 2
+ */
+export default function differenceInCalendarISOWeekYears(
+  dirtyDateLeft: Date | number,
+  dirtyDateRight: Date | number
+): number {
+  requiredArgs(2, arguments)
+
+  return getISOWeekYear(dirtyDateLeft) - getISOWeekYear(dirtyDateRight)
+}