code: def prepare_data(self) -> None:
      self.datamodule.prepare_data()
  
file_path: opacus/opacus/lightning.py
imports: from typing import Any, Optional
  import pytorch_lightning
  import torch
  from opacus.data_loader import DPDataLoader
label_desc: Use image node_id 2 for calling the DPLightningDataModule obj's underlying member method code with example usage: obj.prepare_data() without return types