public function scriptTag($content, $headers = null, $nonce = null)
    {
        if ($headers !== null && $this->shouldAppendNonce($headers)) {
            if (!$nonce) {
                throw new \Exception(
                    'Content-Security-Policy is script-src '.
                    'inline-unsafe but nonce value not provided.'
                );
            }
            
            return "\n<script type=\"text/javascript\" nonce=\"$nonce\">$content</script>";
        }
        return "\n<script type=\"text/javascript\">$content</script>";
    }