public function zip(string $zip, array $collections = []): MediaStream 	{ 		$zip = MediaStream::create($this->generateFileName($zip));  		$collections = $collections === [] ? $this->resolveMediaConfig() : $collections;  		foreach ($collections as $collection) { 			$collection = is_string($collection) ? $collection : $collection['collection'];  			$zip->addMedia($this->files($collection)); 		}  		return $zip; 	}