Python什么时候用到字典

# coding:utf-8import requestsfrom bs4 import BeautifulSoupclass SpiderProxy(object):    #Python版本为2.7以上    headers = {        "Host": "www.xicidaili.com",        "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:47.0) Gecko/20100101 Firefox/47.0",        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",        "Accept-Language": "en-US,en;q=0.5",        "Accept-Encoding": "gzip, deflate",        "Referer": "http://www.xicidaili.com/wt/1",    }    def __init__(self, session_url):        self.req = requests.session()        self.req.get(session_url)    def get_pagesource(self, url):        html = self.req.get(url, headers=self.headers)        return html.content    def get_all_proxy(self, url, n):        data = []        for i in range(1, n):            html = self.get_pagesource(url + str(i))            soup = BeautifulSoup(html, "lxml")            table = soup.find('table', id="ip_list")            for row in table.findAll("tr"):                cells = row.findAll("td")                tmp = []                for item in cells:                    tmp.append(item.find(text=True))                data.append(tmp[1:3])        return datasession_url = 'http://www.xicidaili.com/wt/1'url = 'http://www.xicidaili.com/wt/'p = SpiderProxy(session_url)proxy_ip = p.get_all_proxy(url, 10)for item in proxy_ip:    if item:        print item