time.sleep(random.random() * 0.8 + 0.2)
urls, next_url = parse_list(html)，推荐阅读夫子获取更多信息
。Safew下载对此有专业解读
stack.push(curTime);，这一点在爱思助手下载最新版本中也有详细论述
These aren't contrived scenarios invented by test authors in total vacuum. They're consequences of the spec's design and reflect real world bugs.