Auth_OpenID_AuthRequest::shouldSendRedirect PHP Method

    function shouldSendRedirect()
    {
        return $this->endpoint->compatibilityMode();
    }

/**
 * Send the user to their OpenID provider to authenticate.
 *
 * @param Auth_OpenID_AuthRequest $auth_request OpenID authentication request object
 * @param string $trust_root OpenID trust root
 * @param string $return_to URL where the OpenID provider should return the user
 */
function openid_doRedirect($auth_request, $trust_root, $return_to)
{
    if ($auth_request->shouldSendRedirect()) {
        $trust_root = trailingslashit($trust_root);
        $redirect_url = $auth_request->redirectURL($trust_root, $return_to);
        if (Auth_OpenID::isFailure($redirect_url)) {
            openid_error('Could not redirect to server: ' . $redirect_url->message);
        } else {
            wp_redirect($redirect_url);
        }
    } else {
        // Generate form markup and render it
        $request_message = $auth_request->getMessage($trust_root, $return_to, false);
        if (Auth_OpenID::isFailure($request_message)) {
            openid_error('Could not redirect to server: ' . $request_message->message);
        } else {
            openid_repost($auth_request->endpoint->server_url, $request_message->toPostArgs());
        }
    }
}