code: def Close(self, abort=False):
      
      if abort:
        # Prevent join_thread() from blocking.
        self._queue.cancel_join_thread()
  
      self._queue.close()
      self._queue.join_thread()
docs: Closes the queue.
  
      This needs to be called from any process or thread putting items onto
      the queue.
  
      Args:
        abort (Optional[bool]): True if the close was issued on abort.