AttributeError: 'tuple' object has no attribute 'to'

I got this error while trying to train a GAN model:

    run(config)
  File "t.py", line 417, in run
    x, y = x.to(device), y.to(device)
AttributeError: 'tuple' object has no attribute 'to'

Based on the error message it seems that either one of the used objects (x or y) or both are a tuple instead of tensors.
Could you check the type and make sure the to() operation is only called on tensors directly?