get weeksInLocalWeekYear() {
    return this.isValid
      ? weeksInWeekYear(
          this.localWeekYear,
          this.loc.getMinDaysInFirstWeek(),
          this.loc.getStartOfWeek()
        )
      : NaN;
  }
Returns the number of weeks in this DateTime's local week year
@example DateTime.local(2020, 6, {locale: 'en-US'}).weeksInLocalWeekYear //=> 52
@example DateTime.local(2020, 6, {locale: 'de-DE'}).weeksInLocalWeekYear //=> 53
@type {number}