code: def forward(self, x: Tensor) -> Tensor:
      return self.classification_head(x.detach().flatten(start_dim=1))
  
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 2 for calling the OnlineLinearClassifier obj's underlying member method code with example usage: obj.forward(x) and returns: self