get domains

# coding: utf-8
import requests
from lxml import html
day = 21
month = 12
year = 2016
for i in range(6000):
    print i
    content = requests.get('http://domains-by-day.com/%d-%d-%d/domains-%d.html' % (year, month, day, i)).text
    tree = html.fromstring(content)
    domains = tree.xpath('//tr')
    if len(domains) < 10:
        break
    for domain in domains:
        temp = domain.xpath('td/a')
        #print temp
        if len(temp) < 1:
            continue
        b = temp[0].xpath('text()')
        open("domains.txt", "a").write(b[0].lower() + "\n")