old_contents: def xlsx_export_action(modeladmin, request, queryset):
  
      from django.http import HttpResponse
      from import_export.formats import base_formats
      formats = modeladmin.get_export_formats()
      file_format = base_formats.XLSX()
  
      export_data = modeladmin.get_export_data(file_format, queryset, request=request)
      content_type = file_format.get_content_type()
      # Django 1.7 uses the content_type kwarg instead of mimetype
      try:
          response = HttpResponse(export_data, content_type=content_type)
      except TypeError:
          response = HttpResponse(export_data, mimetype=content_type)
      response['Content-Disposition'] = 'attachment; filename=%s' % (
          modeladmin.get_export_filename(file_format),
      )
      return response
  xlsx_export_action.short_description = "Export selected rows to Excel"
new_contents: from django.http import HttpResponse
  from import_export.formats import base_formats
  
  
  def xlsx_export_action(modeladmin, request, queryset):
  
      formats = modeladmin.get_export_formats()
      file_format = base_formats.XLSX()
  
      export_data = modeladmin.get_export_data(file_format, queryset, request=request)
      content_type = file_format.get_content_type()
      # Django 1.7 uses the content_type kwarg instead of mimetype
      try:
          response = HttpResponse(export_data, content_type=content_type)
      except TypeError:
          response = HttpResponse(export_data, mimetype=content_type)
      response['Content-Disposition'] = 'attachment; filename=%s' % (
          modeladmin.get_export_filename(file_format),
      )
      return response
  xlsx_export_action.short_description = "Export selected rows to Excel"
subject: Undo previous commit. It didn't work.