def to_s
      String.new.tap do |result|
        result << header * '|' << "\n"
        records.each do |record|
          result << record * '|' << "\n"
        end
      end
    end
def to_s
      String.new.tap do |result|
        result << header * '|' << "\n"
        records.each do |record|
          result << record * '|' << "\n"
        end
      end
    end
Returns a string with the export data