//public DateTimeSeries(NdArray<long> array, DType dtype=null)
// : this(new Series<long>(array))
//{
//}
public DateTimeSeries(BaseSeries <long> source, DType dtype = null)
: base(source, getter: DateTime64.ToDateTime, setter: DateTime64.ToDateTime64, dtype: dtype ?? DType.DateTime64)
{
}
public DataMap(DataFrame df, BaseSeries <K> keys, BaseSeries <V> values)
{
this.DataFrame = df;
this.keys = keys;
this.values = values;
}