code: def build(self):
      image, label = self.data_loader()
  
      image = image.to("cuda")
      label = label.to("cuda")
  
      logits, label = self.model(image, label)
      logits = self.combine_margin(logits, label) * 64
      loss = self.cross_entropy(logits, label)
  
      loss.backward()
      return loss
  
file_path: insightface/recognition/arcface_oneflow/graph.py
imports: import oneflow
  import oneflow.nn
label_desc: Use image node_id 2 for calling the TrainGraph obj's underlying member method code with example usage: obj.build() and returns: loss