OpenNIC server list recuperator

#!/usr/bin/env python3
# -*- coding: UTF-8 -*-

import sys
import requests  # http://docs.python-requests.org/en/master/
from bs4 import BeautifulSoup  # http://www.crummy.com/software/BeautifulSoup/

# OpenNIC url
url = 'https://servers.opennicproject.org'

# proxies
proxies = {}
#proxies = {'http': '127.0.0.1:3128', 'https': '127.0.0.1:3128'}  # <-- example simple HTTP proxy
#proxies = {'http': 'socks5://127.0.0.1:8080', 'https': 'socks5://127.0.0.1:8080'}  # <-- example with SockV5 proxy (pip install -U pysocks)
# DNS are not proxified !

# init result vars
ip_v4 = []
ip_v6 = []

# request
r = requests.get(url=url, proxies=proxies)

# good response ?
if r.status_code == 200:
    # parse response
    bs = BeautifulSoup(r.text, "html.parser")
    # find all running servers
    server_list = bs.find_all('p', class_='norm')
    # is there at least one ?
    if len(server_list) > 0:
        # for each one
        for server in server_list:
            # find ipv4
            ipv4 = str(server.find('span', class_='ipv4').text).strip()
            ipv6 = str(server.find('span', class_='ipv6').text).strip()
            if ipv4:
                ip_v4.append(ipv4)
            if ipv6:
                ip_v6.append(ipv6)
    else:  # no one running ...
        print('No running server !', file=sys.stderr)
        sys.exit(-2)
else:  # not a good response
    print('Error receiving from : ' + url, file=sys.stderr)
    sys.exit(-1)

# show ipv4 list
print('ipv4 :')
for ipv4 in ip_v4:
    print(ipv4)
#
print()
# show ipv6 list
print('ipv6 :')
for ipv6 in ip_v6:
    print(ipv6)