code: function separate (from, to) {
    from = this.toDate(from);
    to   = this.toDate(to);
    if (!from || !to) {
      return null;
    }
    return separateFn(from, to, this.startMonth);
  }
docs: 期間をブロックごとに分割(年度、月、日)します
  
  @method separate
  @param  {DATE}   from
  @param  {DATE}   to
  @return {Object} {
  days   : [days1..., days2...],
  months : [months1..., months2...],
  years  : [years...]
  }