code: def validation_step(self, batch, batch_idx):
      return None
  
file_path: life2vec/src/models/dummy.py
imports: from pytorch_lightning import LightningModule
  import torch
  import time
  from torch.nn.functional import cross_entropy
  import logging
label_desc: Use image node_id 4 for calling the DummyModel obj's underlying member method code with example usage: obj.validation_step(batch, batch_idx) and returns: None