如何解决ValueError: not enough values to unpack (expected 4, got 2)

出现的报错信息

Traceback (most recent call last):
  File "rain.py", line 263, in 
    main()
  File "train.py", line 260, in main
    train(args, model, train_loader, test_loader, boardio, textio, checkpoint)
  File "train.py", line 144, in train
    train_loss, train_loss_template, train_loss_source = train_one_epoch(args, model, train_loader, optimizer)
  File "train.py", line 104, in train_one_epoch
    masked_template, masked_source, predicted_mask_template, predicted_mask_source= model(template, source)
ValueError: not enough values to unpack (expected 4, got 2)

Process finished with exit code 1

报错处代码

    for i, data in enumerate(tqdm(train_loader)):
        template, source, igt, gt_mask_template, gt_mask_source = data

        template = template.to(args.device)
        source = source.to(args.device)
        igt = igt.to(args.device)                    # [source] = [igt]*[template]
        gt_mask_template = gt_mask_template.to(args.device)
        gt_mask_source = gt_mask_source.to(args.device)

        masked_template, masked_source, predicted_mask_template, predicted_mask_source= model(template, source)  #报错

请问是哪里出问题了？

model(template, source)
看看这个返回了什么
应该返回的不是四元组，而是二元组（即你不能通过4个变量接收）