code: async def forget(request, response):
      
      identity_policy = request.config_dict.get(IDENTITY_KEY)
      if identity_policy is None:
          text = ("Security subsystem is not initialized, "
                  "call aiohttp_security.setup(...) first")
          # in order to see meaningful exception message both: on console
          # output and rendered page we add same message to *reason* and
          # *text* arguments.
          raise web.HTTPInternalServerError(reason=text, text=text)
      await identity_policy.forget(request, response)
docs: Forget previously remembered identity.
  
      Usually it clears cookie or server-side storage to forget user
      session.