def get_bdstoken(cookie):
url = const.PAN_REFERER<EOL>req = net.urlopen(url, headers={'<STR_LIT>': cookie.header_output()})<EOL>if req:<EOL><INDENT>return parse_bdstoken(req.data.decode())<EOL><DEDENT>else:<EOL><INDENT>return None<EOL><DEDENT>
从/disk/home页面获取bdstoken等token信息

    这些token对于之后的请求非常重要.