code: def pool_dataloader(self):
      return DataLoader(
          self.active_set.pool, batch_size=self.hparams.batch_size
      )
  
imports: import copy
  from dataclasses import dataclass, asdict
  import numpy
  import pytest
  import torch
  from baal.active import ActiveLearningDataset
  from baal.utils.pytorch_lightning import ActiveLightningModule, BaalTrainer, ResetCallback, BaaLDataModule
  from pytorch_lightning import LightningModule
  from torch.utils.data import Dataset, DataLoader
  from torchvision.models import vgg16
label_desc: Use image node_id 3 for calling the SimplePytorchLightning obj's underlying member method code with example usage: obj.pool_dataloader() and returns: DataLoader