human
I wrote the below code

    def parse_share_page(content):
        tree = html.fromstring(content)
        script_sel = CSS('script')
        scripts = script_sel(tree)
        for script in scripts:
            if (script.text and ((script.text.find('viewsingle_param') > (-1)) or (script.text.find('mpan.viewlist_param') > (-1)))):
                break
        else:
            logger.warn('pcs.parse_share_page:    failed    to    get    filelist,    %s', url)
            return None
        start = script.text.find('viewsingle_param.list=JSON.parse(')
        end = script.text.find(');mpan.viewsingle_param.username')
        if ((start == (-1)) or (end == (-1))):
            start = script.text.find('listArr:JSON.parse(')
            end = script.text.find('),rootPath:')
            if ((start == (-1)) or (end == (-1))):
                return None
            else:
                json_str = script.text[(start + 19):end]
        else:
            json_str = script.text[(start + 33):end]
        try:
            return json.loads(json.loads(json_str))
        except ValueError:
            logger.warn(traceback.format_exc())
            return None
    url = ''.join([const.PAN_URL, 'wap/link', '?shareid=', shareid, '&uk=', uk, '&third=0'])
    req = net.urlopen(url, headers={'Cookie': cookie.header_output(), 'Referer': const.SHARE_REFERER})
    if req:
        return parse_share_page(req.data.decode())
    else:
        return None

What's a good function header?

=====
Here's a good function header?
assistant
#Here's a good function header.

def list_share_single_file(cookie, tokens, uk, shareid):