public function getLibSrc($ver)
    {
        if (!$this->isValidVersion($ver)) {
            throw new \Exception(
                sprintf(
                    'Invalid library version provided "%s"',
                    $ver
                )
            );
        }

        $options = $this->options;
        $cdnUrl = rtrim($options['cdn-base'], '/').'/'.
            trim($options['cdn-subfolder'], '/').'/'.
            $ver.'/'.
            trim($options['cdn-file-path'], '/');

        return $cdnUrl;
    }