def fetch(self, wait=0):
        """
        get the task result objects.
        :param int wait: how many milliseconds to wait for a result
        :return: an unsorted list of task objects
        """
        if self.started:
            return fetch(self.id, wait=wait, cached=self.cached)
get the task result objects.
        :param int wait: how many milliseconds to wait for a result
        :return: an unsorted list of task objects