class DateTimeColumn extends AbstractColumn<DateTimeColumn, LocalDateTime> implements DateTimeMapFunctions,
        DateTimeFilters,
        TemporalFillers<LocalDateTime, DateTimeColumn>,
        CategoricalColumn<LocalDateTime> {

  @Override
  public int countUnique() {
    LongSet ints = new LongOpenHashSet(data.size());
    for (long i : data) {
      ints.add(i);
    }
    return ints.size();
  }

  private  DateTimeColumn(String name, LongArrayList data);

}