rabbitpy使用purge不生效

#! /usr/bin/env python3
# -*- coding:utf-8 -*
import rabbitpy
import sys

url = 'amqp://guest:guest@localhost:5672/%2F'
connecttion = rabbitpy.Connection(url)
channel = connecttion.channel()

queue = rabbitpy.Queue(channel,'example')
# print(message.properties)
# sys.exit(0)
# queue.purge()
# sys.exit(0)
while len(queue) > 0:
    message = queue.get(True)

    # print(message)
    # sys.exit(0)
    message.pprint()
    # print('message:')
    # print('ID: %s' % message.properties['message_id'])
    # print('Time: %s' % message.properties['timestamp'].isoformat())
    # print("Body:%s" % message.body)
    message.ack() #不确认的话purge()是不会生效的
print("hello")
queue.purge()