def validation_step()

in train/models/slip_detect.py [0:0]


    def validation_step(self, batch, batch_idx):
        images, targets, sn = batch
        output = self.forward(images)
        val_loss = self.criterion(output, targets)

        self.val_accuracy(output.argmax(dim=1), targets)

        self.log(
            "val_loss",
            val_loss,
            on_epoch=True,
            on_step=False,
            prog_bar=True,
            logger=True,
        )
        self.log(
            "val_acc",
            self.val_accuracy,
            on_epoch=True,
            on_step=False,
            prog_bar=True,
            logger=True,
        )