protected function block(OutputBlock $block)
    {
        if (empty($block->lines) && empty($block->children)) {
            return;
        }

        $this->currentBlock = $block;

        $pre = $this->indentStr();

        if (! empty($block->selectors)) {
            $this->blockSelectors($block);

            $this->indentLevel++;
        }

        if (! empty($block->lines)) {
            $this->blockLines($block);
        }

        if (! empty($block->children)) {
            $this->blockChildren($block);
        }

        if (! empty($block->selectors)) {
            $this->indentLevel--;

            if (empty($block->children)) {
                $this->write($this->break);
            }

            $this->write($pre . $this->close . $this->break);
        }
    }