code: def test_step(self, batch, batch_idx):
      x, y = batch
      y_hat = self.backbone(x)
      loss = self.cal_loss(y_hat, y)
      self.log("test_loss", loss)
  
file_path: insightface/reconstruction/gaze/models.py
imports: import pytorch_lightning
  from pytorch_lightning.callbacks import ModelCheckpoint
  from pytorch_lightning.callbacks import LearningRateMonitor
  from pytorch_lightning.loggers import TensorBoardLogger
  import torch
  import torch.nn
  import timm
label_desc: Use image node_id 6 for calling the GazeModel obj's underlying member method code with example usage: obj.test_step(batch, batch_idx) without return types