code: def training_step(self, batch):
      output = self.forward(batch)
      loss = torch.sum(output)
      self.log("loss", loss)
      return loss
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from torch.utils.data import DataLoader
  from torchmetrics import Accuracy
  from ray import train
  from ray.train.lightning._lightning_utils import import_lightning
label_desc: Use image node_id 3 for calling the DoubleLinearModule obj's underlying member method code with example usage: obj.training_step(batch) and returns: loss