Auth_OpenID_Message::setArg PHP Method

    function setArg($namespace, $key, $value)
    {
        // Set a single argument in this namespace
        $namespace = $this->_fixNS($namespace);
        if (Auth_OpenID::isFailure($namespace)) {
            return $namespace;
        } else {
            $this->args->set(array($namespace, $key), $value);
            if ($namespace !== Auth_OpenID_BARE_NS) {
                $this->namespaces->add($namespace);
            }
            return true;
        }
    }

	function getCancelURL()
	{
		if (!$this->return_to) {
			return new Auth_OpenID_NoReturnToError();
		}

		if ($this->immediate) {
			return new Auth_OpenID_ServerError(null,
                                               "Cancel is not an appropriate \
                                               response to immediate mode \
                                               requests.");
		}

		$response = new Auth_OpenID_Message(
		$this->message->getOpenIDNamespace());
		$response->setArg(Auth_OpenID_OPENID_NS, 'mode', 'cancel');
		return $response->toURL($this->return_to);
	}