code: def set_theme(request):
      
      next = request.POST.get('next', request.GET.get('next'))
  
      if not is_safe_url(url=next, host=request.get_host()):
          next = request.META.get('HTTP_REFERER')
  
          if not is_safe_url(url=next, host=request.get_host()):
              next = '/'
  
      response = http.HttpResponseRedirect(next)
  
      if request.method == 'POST':
          theme = request.POST.get('theme', None)
  
          if theme:
              if hasattr(request, 'session'):
                  request.session['DJANGO_BOOTSTRAP_UI_THEME'] = theme
              else:
                  response.set_cookie('DJANGO_BOOTSTRAP_UI_THEME', theme)
  
      return response
docs: Redirect to a given url while setting the chosen theme in the session or cookie. The url and the theme identifier
      need to be specified in the request parameters.
  
      Since this view changes how the user will see the rest of the site, it must only be accessed as a POST request. If
      called as a GET request, it will redirect to the page in the request (the 'next' parameter) without changing any
      state.