code: def validation_step(self, batch, batch_idx: int):
      print(f"validation_step {self.name}")
      self._call_count["validation"] += 1
      assert self.current_epoch in self.expected_epochs
      return {k: torch.ones(2, 3) for k in self.validation_keys}
  
imports: import unittest
  from typing import List
  import pytorch_lightning
  import torch
  import torch.nn
  import torch.optim
  from reagent.reporting import CompoundReporter, ReporterBase
  from reagent.training import MultiStageTrainer, ReAgentLightningModule
  from torch.utils.data import DataLoader, TensorDataset
label_desc: Use image node_id 6 for calling the DummyTrainer obj's underlying member method code with example usage: obj.validation_step(batch, batch_idx) and returns: unknown