kukudm.com downloader

kukudm.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed Sep 20 00:40:18 2017

@author: qzane
"""

import requests
from lxml import etree
import re
import os,sys
from multiprocessing import Pool


TIMEOUT = 10.0
RETRY = 5
WORKERS = 3
WORKER = Pool(WORKERS)

def http_get(url):
    for i in range(RETRY):
        try:
            page = requests.get(url, timeout=TIMEOUT)
            break
        except Exception as e:
            if i == RETRY-1:
                raise(e)
    return page

def get_commic(url='http://comic.kukudm.com/comiclist/2044/index.htm'):
    assert('comic.kukudm.com' in url)
    assert('comiclist' in url)
    assert('index.htm' in url)
    
    result = {'name':'', 'chapters':[]}
    
    page = http_get(url)
        
    page = page.content.decode('gbk')
    tree = etree.HTML(page)
    
    try:
        name = tree.xpath('//title/text()')[0]
        if '|' in name:
            name = name.split('|')[0]
        result['name'] = name
    except:
        print('name not found!')
        
    try:
        dds = tree.xpath('//dl[@id="comiclistn"]/dd')
        for dd in dds:
            chapter_name = dd.xpath('./a/text()')[0]
            chapter_url = 'http://comic.kukudm.com'+ \
                           dd.xpath('./a/@href')[0]
            result['chapters'].append((chapter_name, chapter_url))
    except:
        print('chapters err')
    
    return result

def get_chapter(url='http://comic.kukudm.com/comiclist/2044/43474/1.htm'):
    assert('comic.kukudm.com' in url)
    assert('comiclist' in url)
    assert(not 'index.htm' in url)
    
    pages = []
    
    while(1):
        page = http_get(url).content.decode('gbk')
        
        img = 'http://n.1whour.com/' + \
              re.findall(r'newkuku.+?\.jpg',page)[0]
              
              
        pages.append(img)
        
        print('get page:'+str(len(pages)))
        
        tree = etree.HTML(page)
        
        url = 'http://comic.kukudm.com' + \
              tree.xpath(r'//img[@src="/images/d.gif"]/parent::a/@href')[0]
        
        if 'exit' in url:
            break

        
    return pages

def download_chapter(paras):
    url, path = paras
    pages = get_chapter(url)
    for no, img in enumerate(pages):
        page = http_get(img)
        fname = os.path.join(path, str(no)+'.jpg')
        with open(fname, 'wb') as f:
            f.write(page.content)
        print(fname)
        
    
    

def main():
    if len(sys.argv) >= 2:
        url = sys.argv[1]
    else:
        url = 'http://comic.kukudm.com/comiclist/2044/index.htm'
    
    if len(sys.argv) >= 3:
        path = sys.argv[2]
    else:
        path = '.'
    
    
    commic = get_commic(url)
    
    print('name:', commic['name'])
    
    path = os.path.join(path, commic['name'])
    
    if not os.path.isdir(path):
        os.mkdir(path)
    
    jobs = []
    
    for chapter in commic['chapters']:
        c_path = os.path.join(path, chapter[0])
        if not os.path.isdir(c_path):
            os.mkdir(c_path)
            
        jobs.append((chapter[1],c_path))
    
    tuple(map(download_chapter, jobs))
    #WORKER.map(download_chapter, jobs)
    #total = len(jobs)
    #for no,_ in enumerate(WORKER.imap_unordered(download_chapter, jobs)):
    #    print('Done %d/%d: %.2f%%'%(no+1, total, float(no+1)/total*100))
    
                     
    
if __name__ == '__main__':
    main()
        

when using WORKER.imap_unordered, the first three jobs will get error saying:
AttributeError: Can't get attribute 'download_chapter' on <module 'main' from 'kukudm.py'>

Someone can tell me why?