code: function isSeasonHoliday (date) {
    date = this.toDate(date);
    if (!date) {
      return false;
    }
  
    var season = this._seasonHoliday;
  
    if (!season) {
      return false;
  
    } else if (typeof season === 'function') {
      return season(date);
  
    } else {
      var key = (date.getMonth() + 1) * 100 + date.getDate() * 1;
      return season[key] || false;
    }
  }
docs: 年末年始・お盆の休日判定
  @method isSeasonHoliday
  @param  {DATE}    date
  @return {Boolean} isClose