code: def fetch(self, failures=True, wait=0):
          
          if self.started:
              return fetch_group(self.group, failures=failures, wait=wait, count=self.length(), cached=self.cached)
docs: 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