public static function for_extension($extension)
    {
        $classes = ClassInfo::subclassesFor(DataFormatter::class);
        array_shift($classes);
        $sortedClasses = [];
        foreach ($classes as $class) {
            $sortedClasses[$class] = Config::inst()->get($class, 'priority');
        }
        arsort($sortedClasses);
        foreach ($sortedClasses as $className => $priority) {
            $formatter = new $className();
            if (in_array($extension, $formatter->supportedExtensions())) {
                return $formatter;
            }
        }
    }