How to use the nhentai.logger.logger.debug function in nhentai

def doujinshi_parser(id_):
    if not isinstance(id_, (int,)) and (isinstance(id_, (str,)) and not id_.isdigit()):
        raise Exception('Doujinshi id({0}) is not valid'.format(id_))

    id_ = int(id_)
    logger.log(15, 'Fetching doujinshi information of id {0}'.format(id_))
    doujinshi = dict()
    doujinshi['id'] = id_
    url = '{0}/{1}/'.format(constant.DETAIL_URL, id_)

    try:
        response = request('get', url)
        if response.status_code in (200, ):
            response = response.content
        else:
            logger.debug('Slow down and retry ({}) ...'.format(id_))
            time.sleep(1)
            return doujinshi_parser(str(id_))

    except Exception as e:
        logger.warn('Error: {}, ignored'.format(str(e)))
        return None

    html = BeautifulSoup(response, 'html.parser')
    doujinshi_info = html.find('div', attrs={'id': 'info'})

    title = doujinshi_info.find('h1').text
    subtitle = doujinshi_info.find('h2')

    doujinshi['name'] = title
    doujinshi['subtitle'] = subtitle.text if subtitle else ''

def __api_suspended_search_parser(keyword, sorting, page):
    logger.debug('Searching doujinshis using keywords {0}'.format(keyword))
    result = []
    i = 0
    while i < 5:
        try:
            response = request('get', url=constant.SEARCH_URL, params={'query': keyword, 'page': page, 'sort': sorting}).json()
        except Exception as e:
            i += 1
            if not i < 5:
                logger.critical(str(e))
                logger.warn('If you are in China, please configure the proxy to fu*k GFW.')
                exit(1)
            continue
        break

    if 'result' not in response:
        raise Exception('No result in response')

def search_parser(keyword, sorting='date', page=1):
    logger.debug('Searching doujinshis of keyword {0}'.format(keyword))
    response = request('get', url=constant.SEARCH_URL, params={'q': keyword, 'page': page, 'sort': sorting}).content

    result = _get_title_and_id(response)
    if not result:
        logger.warn('Not found anything of keyword {}'.format(keyword))

    return result

if sorting == 'date':
        sorting = ''

    for p in range(1, max_page + 1):
        if sys.version_info >= (3, 0, 0):
            unicode_ = str
        else:
            unicode_ = unicode

        if isinstance(tag_name, (str, unicode_)):
            logger.debug('Fetching page {0} for doujinshi with tag \'{1}\''.format(p, tag_name))
            response = request('get', url='%s/%s/%s?page=%d' % (constant.TAG_URL[index], tag_name, sorting, p)).content
            result += _get_title_and_id(response)
        else:
            for i in tag_name:
                logger.debug('Fetching page {0} for doujinshi with tag \'{1}\''.format(p, i))
                response = request('get',
                                   url='%s/%s/%s?page=%d' % (constant.TAG_URL[index], i, sorting, p)).content
                result += _get_title_and_id(response)

        if not result:
            logger.error('Cannot find doujinshi id of tag \'{0}\''.format(tag_name))
            return

    if not result:
        logger.warn('No results for tag \'{}\''.format(tag_name))

    return result