code: function(daysSinceHebrewBase) {
      var parts, months, year;
      parts = daysSinceHebrewBase * DAY_LENGTH;
      months = parts / MONTH_LENGTH;
      months = Math.floor(months);
      year = months2year(months);
      months = year2months(year);
      return months;
    }
docs: days - since Hebrew base (29/5/0) zero-based
  returns months - zero-based