code: def on_train_start(self) -> None:
      assert isinstance(
          self.bn_layer, torch.nn.modules.batchnorm.SyncBatchNorm
      )
  
file_path: pytorch-lightning/tests/parity_pytorch/test_sync_batchnorm_parity.py
imports: import torch
  import torch.nn
  from lightning.pytorch import LightningModule, Trainer, seed_everything
  from torch.utils.data import DataLoader, DistributedSampler
  from parity_pytorch import RunIf
label_desc: Use image node_id 2 for calling the SyncBNModule obj's underlying member method code with example usage: obj.on_train_start() without return types