Geshi hack - Remove existing lines?

In the Geshi hack, you mention adding

// Replace all newlines to a common form.
$code = str_replace(">", ">", $code);
$code = str_replace("&lt;", "<", $code);
$code = str_replace("&amp;", "&", $code);
$code = str_replace("&#39;", "'", $code);
$code = str_replace("&quot;", "\"", $code);

but there are already two existing lines.

// Replace all newlines to a common form.
$code = str_replace("\r\n", "\n", $this->source);
$code = str_replace("\r", "\n", $code);

Are those lines supposed to be replaced or appended to?