code: def preview_page_version(request, revision_id):
      
      revision = get_object_or_404(PageRevision, pk=revision_id)
  
      if not revision.page.permissions_for_user(request.user).can_publish():
          raise PermissionDenied
  
      page                = revision.as_page_object()
      request.revision_id = revision_id
  
      return page.serve_preview(request, page.default_preview_mode)
docs: Returns GET response for specified page preview.
  
      :param request: the request instance.
      :param reversion_pk: the page revision ID.
      :rtype: django.http.HttpResponse.