protected function getIndentation()
    {
        if ($this->document) {
            if ($this->document->getConfig()->get(FormatterInterface::CFG_USE_TABS)) {
                $indentation = "\t";
            } else {
                $indentation = str_repeat(' ', $this->document->getConfig()->get(FormatterInterface::CFG_INDENTATION));
            }

            return str_repeat($indentation, $this->indentation);
        }
    }