public function reply(HTTPRequest $request)
    {
        // Extract parent comment from reply and build this way
        if ($parentID = $request->param('ParentCommentID')) {
            /** @var Comment $comment */
            $comment = DataObject::get_by_id(Comment::class, $parentID, true);
            if ($comment) {
                return $this->ReplyForm($comment);
            }
        }
        return $this->httpError(404);
    }