Someone

function woohoo($content){  if($content == '<!--blah-->')    {    	$content = preg_replace_callback('|<!--blah-->|i', 'foobar', $content);  	}  elseif($content == '<p><!--blah--></p>')    {    	$content = preg_replace_callback('|(<p>)?<!--blah-->(</p>)?|i', 'foobar', $content);  	}  return $content;}