code: def validation_step(self, batch, batch_idx):
      x, y = batch
      logits = self.forward(x)
      self.log("val_loss", F.cross_entropy(logits, y), prog_bar=False)
      self.log("val_acc", self.valid_acc(logits, y), prog_bar=True)
  
imports: import operator
  import torch
  import torch.nn.functional
  from lightning.pytorch import LightningModule
  from lightning_utilities.core.imports import compare_version
  from torch import nn
  from torchmetrics import Accuracy, MeanSquaredError
label_desc: Use image node_id 5 for calling the ClassificationModel obj's underlying member method code with example usage: obj.validation_step(batch, batch_idx) without return types