web crawler 0.001

#-*- coding:utf-8 -*-
import sys 
import re
import requests
import gevent
from bs4 import BeautifulSoup
import urlparse
import time


global header_info
header_info = {
'User-Agent':'Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.89 Safari/537.36'
}

root_url = 'http://wap.douban.com'

def crawler():
    ''' '''

    r = requests.get(root_url, timeout = 4, headers=header_info)
    if (r.status_code != 200):
        return []
    print r.status_code
    '''
    soup = BeautifulSoup(r.text, 'html.parser')
    selects = [a.attrs.get('href') for a in soup.select('a')]
    '''
    try:
        with open("text.html", "wb") as f:
            f.write(r.content)
    except IOError:
            print("Oops, file error...")

gevent.joinall([
    gevent.spawn(crawler)
])