public function format(OutputBlock $block, SourceMapGenerator $sourceMapGenerator = null)
    {
        $this->sourceMapGenerator = null;

        if ($sourceMapGenerator) {
            $this->currentLine = 1;
            $this->currentColumn = 0;
            $this->sourceMapGenerator = $sourceMapGenerator;
        }

        ob_start();

        $this->block($block);

        $out = ob_get_clean();

        return $out;
    }