def pop_slot(self, slot):
        """ Pop an object from a priority queue for this slot """
        queue = self.pqueues[slot]
        request = queue.pop()
        if len(queue) == 0:
            del self.pqueues[slot]
        return request
 Pop an object from a priority queue for this slot 
stackoverflow/venv/lib/python3.6/site-packages/scrapy/pqueues.py