如何将所有返回值全部print出来

要在代码中打印出所有函数的返回值，可以在每个函数调用后立即使用 `print` 语句来输出返回值。以下是一些关键函数及其返回值的示例：

1. **`make_data_loader` 函数**:

   def make_data_loader(spec, tag=''):
       ...
       return loader
   
   train_loader = make_data_loader(config.get('train_dataset'), tag='train')
   print("Train loader:", train_loader)
   
   val_loader = make_data_loader(config.get('val_dataset'), tag='val')
   print("Validation loader:", val_loader)

2. **`prepare_training` 函数**:

   def prepare_training():
       ...
       return model, optimizer, epoch_start, lr_scheduler
   
   model, optimizer, epoch_start, lr_scheduler = prepare_training()
   print("Model:", model)
   print("Optimizer:", optimizer)
   print("Epoch start:", epoch_start)
   print("LR Scheduler:", lr_scheduler)

3. **`train` 函数**:

   def train(train_loader, model, optimizer, epoch):
       ...
       return train_loss.item()
   
   train_loss_value = train(train_loader, model, optimizer, epoch)
   print("Train loss:", train_loss_value)

4. **`main` 函数**:

   def main(config_, save_path):
       ...
       for epoch in range(epoch_start, epoch_max + 1):
           ...
           train_loss = train(train_loader, model, optimizer, epoch)
           print("Train loss for epoch {}:".format(epoch), train_loss)
           
           if (epoch_val is not None) and (epoch % epoch_val == 0):
               ...
               val_res = eval_psnr(val_loader, model_, data_norm=config['data_norm'], eval_type=config.get('eval_type'), eval_bsize=config.get('eval_bsize'))
               print("Validation PSNR for epoch {}:".format(epoch), val_res)
       
       ...
   
   if __name__ == '__main__':
       ...
       main(config, save_path)

通过在这些关键位置添加 `print` 语句，你可以确保所有重要的返回值都被打印出来，以便于调试和监控程序的运行情况。