Make a Snippet not Render

// plugin.fixedpre.tpl -- implements <fixedpre> tag -- Rahul Dhesi
// http://rahul.rahul.net/modx-hints/fixedpre-tag.html
function quote_meta($a) {
  $lhs = array("<", ">", "[", "]", "!", "{", "}", "`");
  $rhs = array("<", ">", "[", "]", "!", "{", "}", "`");
  $b = str_replace("&", "\255", $a[2]);  //save "&"

  $lhs_preg = array('|<!(!*)fixedpre>|',  '|<!(!*)/fixedpre>|');
  $rhs_preg = array('<$1fixedpre>',  '<$1/fixedpre>');
  $b = preg_replace($lhs_preg, $rhs_preg, $b);
  $b = str_replace($lhs, $rhs, $b);
  return str_replace("\255", "&", $b); // restore "&"
}

$e = &$modx->Event;
if ($e->name == "OnLoadWebDocument") {
  $modx->documentObject['content']=
    preg_replace_callback("#(<fixedpre>)(.*?)(</fixedpre>)#s",
    "quote_meta", $modx->documentObject['content']);
}