code: def default(request):
      
      protocol = request.is_secure() and 'wss://' or 'ws://'
      heartbeat_msg = settings.WS4REDIS_HEARTBEAT and '"{0}"'.format(settings.WS4REDIS_HEARTBEAT) or 'null'
      context = {
          'WEBSOCKET_URI': protocol + request.get_host() + settings.WEBSOCKET_URL,
          'WS4REDIS_HEARTBEAT': mark_safe(heartbeat_msg),
      }
      return context
docs: Adds additional context variables to the default context.