message: Fix bug for pipeline & add docs
diff: @@ -767,7 +767,7 @@ class ThreadChannel(Queue.PriorityQueue):
  while self._stop is False and self._consumer_cursors[
  op_name] - self._base_cursor >= len(self._output_buf):
  try:
  - channeldata = self.get(timeout=0)
  + channeldata = self.get(timeout=0)[1]
  self._output_buf.append(channeldata)
  list_values = list(channeldata.values())
  _LOGGER.debug(
  