code: def step(self, x):
      x = self(x)
      return torch.nn.functional.mse_loss(x, torch.ones_like(x))
  
imports: from typing import Optional
  import torch
  from pytorch_lightning import LightningDataModule, LightningModule
  from torch.utils.data import DataLoader, Dataset, Subset
label_desc: Use image node_id 4 for calling the BoringModel obj's underlying member method code with example usage: obj.step(x) and returns: torch