'Returns this token as a plain string, suitable for storage.
The resulting string includes the token\'s secret, so you should never
send or store this string where a third party can read it.'

def to_string(self):

    items = [('oauth_token', self.key), ('oauth_token_secret', self.secret)]
    if (self.callback_confirmed is not None):
        items.append(('oauth_callback_confirmed', self.callback_confirmed))
    return urlencode(items)
