public function getPrevious()
    {
        $prev = $this;
        $find = false;
        if (!is_null($this->parent)) {
            foreach ($this->parent->content as $c) {
                if ($c === $this) {
                    $find=true;
                    break;
                }
                if (!$find) {
                    $prev = $c;
                }
            }
        }
        return $prev;
    }