public function setIndentStyle($indentStyle)
    {
        if (!in_array($indentStyle, [null, Lexer::INDENT_TAB, Lexer::INDENT_SPACE])) {
            throw new \InvalidArgumentException(
                'indentStyle needs to be null or one of the INDENT_* constants of the lexer'
            );
        }

        $this->indentStyle = $indentStyle;

        return $this;
    }