docs: def appendleft(self, item):
          """Add item to the left side of the GeventDeque.
  
          This method does not block.  Either the GeventDeque grows to
          consume available memory, or if this GeventDeque has and is at
          maxlen, the rightmost item is removed.
          """
          self._deque.appendleft(item)
          self.notEmpty.set()