code: def _chuli_cookie_relation(self, app_id):
          '''
          The current Info and the Info viewed last should have some relation.
          And the last viewed Info could be found from cookie.
          '''
          last_app_uid = self.get_secure_cookie('use_app_uid')
          if last_app_uid:
              last_app_uid = last_app_uid.decode('utf-8')
          self.set_secure_cookie('use_app_uid', app_id)
          if last_app_uid and MPost.get_by_uid(last_app_uid):
              self._add_relation(last_app_uid, app_idf _chuli_cookie_relation(self, app_id):
          '''
          The current Info and the Info viewed last should have some relation.
          And the last viewed Info could be found from cookie.
          '''
          last_app_uid = self.get_secure_cookie('use_app_uid')
          if last_app_uid:
              last_app_uid = last_app_uid.decode('utf-8')
          self.set_secure_cookie('use_app_uid', app_id)
          if last_app_uid and MPost.get_by_uid(last_app_uid):
              self._add_relation(last_app_uid, app_id)
docs: The current Info and the Info viewed last should have some relation.
          And the last viewed Info could be found from cookie.