code: def get_attachment_content(self, request, queryset):
          
  
          return self.dump_report_content(request, self.get_report_data_rows(request, queryset))
docs: Returns the generated file content.
          :param request: The request being processed.
          :param queryset: The model class being processed.
          :return: The report content (usually expressed in raw bytes but could be unicode as well).