public function getTwoFactorAuthenticator($className)
    {
        $object = $this->_loadClass('TwoFactor_' . $className, true);

        if (! $object instanceof TwoFactorAuthenticatorInterface) {
            throw new \Gems_Exception_Coding(sprintf(
                    'The authenticator class %s should be an instance of TwoFactorAuthenticatorInterface.',
                    $className
                    ));
        }

        return $object;
    }