code: def max_date(self, rows: List[Row], column: DateColumn) -> Date:
          
          cell_values = [row.values[column.name] for row in rows]
          if not cell_values:
              return Date(-1, -1, -1)
          if not all([isinstance(value, Date) for value in cell_values]):
              raise ExecutionError(f"Invalid values for date selection function: {cell_values}")
          return max(cell_values)
docs: Takes a list of rows and a column and returns the max of the values under that column in
          those rows.