code: def validation_epoch_end(self, outputs):
      print(f"validation_step_end {self.name}")
      print(outputs)
      for output in outputs:
          assert set(output.keys()) == set(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 7 for calling the DummyTrainer obj's underlying member method code with example usage: obj.validation_epoch_end(outputs) without return types