code: def switch_region(request, region_name,
                    redirect_field_name=auth.REDIRECT_FIELD_NAME):
      
      if region_name in request.user.available_services_regions:
          request.session['services_region'] = region_name
          LOG.debug('Switching services region to %s for user "%s".',
                    region_name, request.user.username)
  
      redirect_to = request.GET.get(redirect_field_name, '')
      if not is_safe_url(url=redirect_to, host=request.get_host()):
          redirect_to = settings.LOGIN_REDIRECT_URL
  
      response = shortcuts.redirect(redirect_to)
      utils.set_response_cookie(response, 'services_region',
                                request.session['services_region'])
      return response
docs: Switches the user's region for all services except Identity service.
  
      The region will be switched if the given region is one of the regions
      available for the scoped project. Otherwise the region is not switched.