code: public static List<Row> minMaxColumns(DataRowsFacade data, String... columns) {
          return aggregate(data, columns, new String[] {"min", "max"});
      }
docs: Returns the min and max of the given columns.
  The list returned is a list of size 2 where each row
  @param data the data to get the max for
  @param columns the columns to get the
  @return