code: async def _client_run_async(self):
          
          # pylint: disable=protected-access
          self._waiting_messages = 0
          async with self._pending_messages_lock:
              self._pending_messages = await self._filter_pending_async()
          if self._backoff and not self._waiting_messages:
              _logger.info("Client told to backoff - sleeping for %r seconds", self._backoff)
              await self._connection.sleep_async(self._backoff)
              self._backoff = 0
          await asyncio.shield(self._connection.work_async())
          return True
docs: MessageSender Link is now open - perform message send
          on all pending messages.
          Will return True if operation successful and client can remain open for
          further work.
  
          :rtype: bool