public function prepend($content = null)
        {
            if (null === $content) {
                return;
            } else if (is_array($content)) {
                foreach (array_reverse($content) as $row) {
                    array_unshift($this->content, $row);
                }
            } else {
                array_unshift($this->content, $content);
            }
            return $this;
        }