// from any read operation.)
func (b *Buffer) UnreadRune() error {
	if b.lastRead <= opInvalid {
		return errors.New("bytes.Buffer: UnreadRune: previous operation was not a successful ReadRune")
	}
	if b.off >= int(b.lastRead) {
		b.off -= int(b.lastRead)
	}
	b.lastRead = opInvalid
	return nil
}

      }
    } finally {
      readCompleteLatch.countDown()
    }
  }

  abstract fun listSource(): Source

  override fun ensureLoaded() {
    if (!listRead.get() && listRead.compareAndSet(false, true)) {
      readTheListUninterruptibly()
    } else {
      try {
        readCompleteLatch.await()
      } catch (_: InterruptedException) {

            var lastDay = moment([year, month, daysInMonth]);
            var lastMonth = moment(firstDay).subtract(1, 'month').month();
            var lastYear = moment(firstDay).subtract(1, 'month').year();
            var daysInLastMonth = moment([lastYear, lastMonth]).daysInMonth();
            var dayOfWeek = firstDay.day();

            //initialize a 6 rows x 7 columns array for the calendar
            var calendar = [];