What should be the value of grad_tensors?
The pytorch code is:
optimizer = optim.Adam(filter(lambda p: p.requires_grad, model.parameters()), lr=args.lr)
optimizer.zero_grad()
cross_entropy_loss=torch.nn.BCELoss(reduction='none')
neg_log_prob= cross_entropy_loss(y_preds, y_PA)
select_loss=neg_log_prob*average_reward
select_loss.backward(grad_tensors=?)
optimizer.step()