code: def on_validation_epoch_end(self):
      avg_loss = torch.stack(self.val_loss_list).mean()
      avg_acc = torch.stack(self.val_acc_list).mean()
      self.log("ptl/val_loss", avg_loss)
      self.log("ptl/val_accuracy", avg_acc)
      self.val_acc_list.clear()
      self.val_loss_list.clear()
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from torch.utils.data import DataLoader
  from torchmetrics import Accuracy
  from ray import train
  from ray.train.lightning._lightning_utils import import_lightning
label_desc: Use image node_id 6 for calling the LightningMNISTClassifier obj's underlying member method code with example usage: obj.on_validation_epoch_end() without return types