def create_sum_row
        line = []
        header.clear_header_cols.each do |col|
          line << @sum_row[col] || ""
        end
        line.flatten.join(';')
      end
def create_sum_row
        line = []
        header.clear_header_cols.each do |col|
          line << @sum_row[col] || ""
        end
        line.flatten.join(';')
      end
Creates the sum_row when the file has been completely processed