Function to escape code for display in a webpage

You must replace every occurance of muppet with code, we can't use "code" because the wiki translates this meaning to highlight the code and it makes a mess of the layout.

function escapeTxtInCodeTag($txt) {

 $callback = function($matches) {
    return '<muppet' . $matches[1] . '>' . htmlentities($matches[2], ENT_QUOTES, 'UTF-8') . '</muppet>';
 };
 $txt = preg_replace_callback('#\<\s*code(.*?)>(.+?)<\s*\/code\s*>#', $callback, $txt);
 return $txt;
}