public function getFiles() {
        static $files;
        if (!isset($files)) {
            $normalizeLevel = function(array $file) use (&$normalizeLevel) {
                if (isset($file['name']) && is_array($file['name'])) {
                    $properties = \array_keys($file);
                    $normalized = [];
                    foreach (\array_keys($file['name']) as $name) {
                        foreach ($properties as $property) {
                            $normalized[$name][$property] = $file[$property][$name];
                        }
                        $normalized[$name] = $normalizeLevel($normalized[$name]);
                    }
                    $file = $normalized;
                }
                return $file;
            };
            $files = [];
            if (isset($_FILES)) {
                foreach ($_FILES as $key => $file) {
                    $files[$key] = $normalizeLevel($file);
                }
            }
        }
        return $files;
    }