function compareMultipleMonth(obj) {
  obj.months.forEach((month, monthi) => {
    month.weeks.forEach((week, weeki) => {
      week.days.forEach((day, dayi) => {
        // @ts-expect-error since we are converting Date to ISO string, but that's okay for our test Date comparisons
        // eslint-disable-next-line no-param-reassign
        obj.months[monthi].weeks[weeki].days[dayi].date =
          obj.months[monthi].weeks[weeki].days[dayi].date.toISOString();
      });
    });
  });
  return obj;
}
@param {{ months: import('../../types/day.js').Month[]}} obj