Spatie\Backup\Tasks\Backup\Zip::add PHP Method

    public function add($files, string $nameInZip = null) : Zip
    {
        if (is_array($files)) {
            $nameInZip = null;
        }
        if (is_string($files)) {
            $files = [$files];
        }
        foreach ($files as $file) {
            if (file_exists($file)) {
                $this->zipFile->addFile($file, $nameInZip) . PHP_EOL;
            }
            $this->fileCount++;
        }
        return $this;
    }