关于简单的爬虫，逻辑上的问题

使用python写的爬虫
import sys

sys.getdefaultencoding()
from re import *

http = PoolManager()
disable_warnings()

def download(url):

result = http.request('GET',url)

htmlStr = result.data.decode('utf-8')

return htmlStr

def analyse(htmlStr):

aList = findall(']*>',htmlStr)

result = []
for a in aList:
g = search('href[\s]*=[\s]*\'"[\'"]',a)
if g != None:
url = g.group(1)
url = 'http://www.weather.com.cn/' + url
result.append(url)
return result
#print(analyse(download('http://www.weather.com.cn/')))
def crawler(url):
print(url)
html = download(url)
urls = analyse(html)
for url in urls:
crawler(url)
crawler('http://www.weather.com.cn/')
为什么程序运行下来后，会不断的循环www.weather.com.cn这个页面，而不会调到子页面
望大佬指教！

输出看看urls列表里面都有什么东西？？