def loss_value(self, x_data, y_true, y_pred):
y_pred = y_pred.view(-<NUM_LIT:1>, y_pred.size(<NUM_LIT:2>))<EOL>y_true = y_true.view(-<NUM_LIT:1>).to(torch.long)<EOL>return F.nll_loss(y_pred, y_true)<EOL>
Calculate a value of loss function