SassScriptFunction::process_arguments PHP Method

    private function process_arguments($input)
    {
        if (is_array($input)) {
            $output = array();
            foreach ($input as $k => $token) {
                $output[$k] = trim($this->process_arguments($token), '\'"');
            }
            return $output;
        }
        $token = $input;
        if ($token === null) {
            return ' ';
        }
        if (!is_object($token)) {
            return (string) $token;
        }
        if (method_exists($token, 'toString')) {
            return $token->toString();
        }
        if (method_exists($token, '__toString')) {
            return $token->__toString();
        }
        if (method_exists($token, 'perform')) {
            return $token->perform();
        }
        return '';
    }