public function crop(array $croppable, $index = 0)
    {
        $coordinates = $croppable['coordinates'][$index];

        $file = new UploadableFile($this->root_path, $croppable['image']);
        $name = $this->makeCropName($file, $coordinates);
        $path = $file->getRootPath() . $name;

        if (!file_exists($path)) {
            $this->doCrop($file, $coordinates, $path);
        }

        return $name;
    }