class_docstr: >>> LitAutoEncoder()  # doctest: +ELLIPSIS +NORMALIZE_WHITESPACE
  LitAutoEncoder(
    (encoder): ...
    (decoder): ...
  )
class_docstr_tok: [">",">",">","LitAutoEncoder","(",")","#","doctest",":","+ELLIPSIS","+NORMALIZE_WHITESPACE","LitAutoEncoder","(","(","encoder",")",":","...","(","decoder",")",":","...",")"]
code: def validation_step(self, batch, batch_idx):
      self._common_step(batch, batch_idx, "val")
  
imports: from os import path
  from typing import Optional, Tuple
  import torch
  import torch.nn.functional
  from lightning.pytorch import LightningDataModule, LightningModule, Trainer, callbacks, cli_lightning_logo
  from lightning.pytorch.cli import LightningCLI
  from lightning.pytorch.demos.mnist_datamodule import MNIST
  from lightning.pytorch.utilities import rank_zero_only
  from lightning.pytorch.utilities.imports import _TORCHVISION_AVAILABLE
  from torch import nn
  from torch.utils.data import DataLoader, random_split
label_desc: Use image node_id 4 for calling the LitAutoEncoder obj's underlying member method code with example usage: obj.validation_step(batch, batch_idx) without return types