It looks like line 6 is the error. "/* DO NOT CHANGE THE LINE ABOVE */"
Remove that last line and give it another shot.
This should work as a bare minimum starting point -
/* PHP CODE HERE */
/* BODY HERE */
$body = <<<EOF
EOF;
Here is another example, if you were going to create one for Google Adsense
/* PHP CODE HERE */
/* BODY HERE */
$body = <<<EOF
<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- 160x600 Portal TEXT/IMAGE -->
<ins class="adsbygoogle"
style="display:inline-block;width:160px;height:600px"
data-ad-client="ca-pub-9999999999999999"
data-ad-slot="1234567890"></ins>
<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>
EOF;
