code: def training_step(
      self, batch, batch_idx
  ) -> Tuple[Tensor, Dict[str, Tensor]]:
      loss, topk = self.shared_step(batch=batch, batch_idx=batch_idx)
      log_dict = {"train_online_cls_loss": loss}
      log_dict.update(
          {f"train_online_cls_top{k}": acc for k, acc in topk.items()}
      )
      return loss, log_dict
  
file_path: lightly/lightly/utils/benchmarking/online_linear_classifier.py
imports: from typing import Dict, Tuple
  from pytorch_lightning import LightningModule
  from torch import Tensor
  from torch.nn import CrossEntropyLoss, Linear
  from lightly.utils.benchmarking.topk import mean_topk_accuracy
label_desc: Use image node_id 4 for calling the OnlineLinearClassifier obj's underlying member method code with example usage: obj.training_step(batch, batch_idx) and returns: loss,  log_dict