get the task result objects from the chain when it finishes. blocks until timeout.
        :param failures: include failed tasks
        :param int wait: how many milliseconds to wait for a result
        :return: an unsorted list of task objects

def fetch(self, failures=True, wait=0):
        """
        get the task result objects from the chain when it finishes. blocks until timeout.
        :param failures: include failed tasks
        :param int wait: how many milliseconds to wait for a result
        :return: an unsorted list of task objects
        """
        if self.started:
            return fetch_group(self.group, failures=failures, wait=wait, count=self.length(), cached=self.cached)