I have just made the updates and i get the following error:
ValueError                                Traceback (most recent call last)
<ipython-input-25-a174178ab267> in <module>
      8         bbox = Variable(bbox).float()
      9         optimizer.zero_grad()
---> 10         output_label, output_bbox = net(images)
     11         loss_label = criterion_label(output_label, labels)
     12         loss_bbox = criterion_bbox(output_bbox, bbox)

ValueError: too many values to unpack (expected 2)