def METHOD_NAME(self, batch, batch_ind):
    x, y = batch
    out = self.post_forward(self.model(x))
    val_loss = self.loss(out, y)
    num_labels = len(self.cfg.data.class_names)
    y = y.view(-1)
    out = self.prob_to_pred(out).view(-1)
    conf_mat = compute_conf_mat(out, y, num_labels)
    return {'val_loss': val_loss, 'conf_mat': conf_mat}