h-entry addon for reply to in wordpress

//attaches in-reply-to classes to the first link in the post
function the_content_in_reply_to_filter($content) {
  return preg_replace('`\<[aA] `','<a class="u-in-reply-to in-reply-to"',$content,1);
}

add_filter( 'the_content', 'the_content_in_reply_to_filter' );