新人请教一下怎么添加判断

原代码：

def extract_features(img_dir, model):
    try:
        cache = Cache('./tmp')
        feats = []
        names = []
        img_list = get_imgs(img_dir)
        total = len(img_list)
        cache['total'] = total
        for i, img_path in enumerate(img_list):
            try:
                norm_feat = model.resnet50_extract_feat(img_path)
                feats.append(norm_feat)
                names.append(img_path.encode())
                cache['current'] = i + 1
                print(f"Extracting feature from image No. {i + 1} , {total} images in total")
            except Exception as e:
                LOGGER.error(f"Error with extracting feature from image {e}")
                continue
        return feats, names
    except Exception as e:
        LOGGER.error(f"Error with extracting feature from image {e}")
        sys.exit(1)

大概位置是下面这里：

def extract_features(img_dir, model):
    try:
        cache = Cache('./tmp')
        feats = []
        names = []
        img_list = get_imgs(img_dir)
        total = len(img_list)
        cache['total'] = total
        #check if img_dir is a image or image_path
        #if it is image, create embedding and return, else, traverse the directory
        for i, img_path in enumerate(img_list):
            #extract feature
        return feats, names
    except Exception as e:
        LOGGER.error(f"Error with extracting feature from image {e}")
        sys.exit(1)

请问一下应该如何写啊？ 判断传入的是图片文件名还是目录