docs: def add_message(request, level, message, extra_tags='', fail_silently=False, *args, **kwargs):
      """
      Attempts to add a message to the request using the 'messages' app.
      """
      if hasattr(request, '_messages'):
          return request._messages.add(level, message, extra_tags, *args, **kwargs)
      if not fail_silently:
          raise MessageFailure('You cannot add messages without installing '
                               'django.contrib.messages.middleware.MessageMiddleware')