'Process an XPATH command (optional server extension) Arguments:
- id: Message id of article
Returns:
resp: server response if successful
path: directory path to article'

def xpath(self, id):

    resp = self.shortcmd(('XPATH    ' + id))
    if (resp[:3] != '223'):
        raise NNTPReplyError(resp)
    try:
        [resp_num, path] = resp.split()
    except ValueError:
        raise NNTPReplyError(resp)
    else:
        return (resp, path)
