code: def parent(self):
          
          parent_id = self._json_data.get('parent_id')
          if parent_id is None:
              raise NotFoundError("Cannot find subprocess for this task '{}', "
                                  "as this task exist on top level.".format(self.name))
          return self._client.activity(pk=parent_id, scope=self.scope_id)
docs: Retrieve the parent in which this activity is defined.
  
          If this is a task on top level, it raises NotFounderror.
  
          :return: a :class:`Activity2`
          :raises NotFoundError: when it is a task in the top level of a project
          :raises APIError: when other error occurs
  
          Example
          -------
          >>> task = project.activity('Subtask')
          >>> parent_of_task = task.parent()