code: def forward(self, batch):
      output = self.l1(batch)
      output = torch.nn.functional.l1_loss(
          output, torch.zeros(output.size()).to(output.device)
      )
      return output
  
imports: import math
  import os
  import re
  from pathlib import Path
  from typing import Any
  import pytest
  import pytorch_lightning
  import torch
  from omegaconf import OmegaConf
  from omegaconf.errors import OmegaConfBaseException
  from pytorch_lightning import Callback
  from pytorch_lightning.loops import _TrainingEpochLoop
  from nemo.constants import NEMO_ENV_VARNAME_VERSION
  from nemo.core.classes import ModelPT
  from nemo.utils.exp_manager import CheckpointMisconfigurationError, LoggerMisconfigurationError, NotFoundError, exp_manager
label_desc: Use image node_id 4 for calling the ExampleModel obj's underlying member method code with example usage: obj.forward(batch) and returns: output