code: def _proxy(self):
          
          if self._context is None:
              self._context = SyncListItemContext(
                  self._version,
                  service_sid=self._solution['service_sid'],
                  list_sid=self._solution['list_sid'],
                  index=self._solution['index'],
              )
          return self._context
docs: Generate an instance context for the instance, the context is capable of
          performing various actions.  All instance actions are proxied to the context
  
          :returns: SyncListItemContext for this SyncListItemInstance
          :rtype: twilio.rest.preview.sync.service.sync_list.sync_list_item.SyncListItemContext