public function copyChapter(Chapter $chapter_org, Chapter $parent, $copy_children, $copyName = null)
    {
        $chapter_copy = new Chapter();
        if (!$copyName) {
            $copyName = $chapter_org->getTitle();
        }
        $chapter_copy->setTitle($copyName);
        $chapter_copy->setText($chapter_org->getText());
        $chapter_copy->setLesson($parent->getLesson());
        $this->insertChapter($chapter_copy, $parent);
        if ($copy_children) {
            $this->copyChildren($chapter_org, $chapter_copy, $copy_children);
        }

        return $chapter_copy;
    }