':return: çšæ·äžæ ïŒè¿åçæåš
:rtype: Column.Iterable'

@property
def columns(self):

    from .column import Column
    if ((self.url is None) or (self.post_num == 0)):
        return
    soup = BeautifulSoup(self._session.get((self.url + 'posts')).text)
    column_list = soup.find('div', class_='column-list')
    column_tags = column_list.find_all('div', class_='item')
    for column_tag in column_tags:
        name = column_tag['title']
        url = column_tag['data-href']
        numbers = column_tag.find('span', class_='des').text.split('\xe2\x80\xa2')
        follower_num = int(re_get_number.match(numbers[0]).group(1))
        if (len(numbers) == 1):
            post_num = 0
        else:
            post_num = int(re_get_number.match(numbers[1]).group(1))
        (yield Column(url, name, follower_num, post_num, session=self._session))
