code: def step(self, batch, batch_idx):
      x = batch
      bs = x.size(0)
      y_hat = self.l1(x)
  
      test_hat = y_hat.cpu().detach()
      assert torch.all(test_hat[:, 0] == 15.0)
      assert torch.all(test_hat[:, 1] == 42.0)
      out = y_hat.sum()
      assert out == (42.0 * bs) + (15.0 * bs)
  
      return out
  
imports: import torch
  from lightning.pytorch.core.module import LightningModule
  from torch import Tensor, nn
  from torch.utils.data import DataLoader, Dataset
label_desc: Use image node_id 3 for calling the DeterministicModel obj's underlying member method code with example usage: obj.step(batch, batch_idx) and returns: out