code: def forward(self, image1: Tensor, image2: Tensor) -> Tensor:
      return self.model(image1) - self.model(image2)
  
file_path: NeuralCompression/tests/conftest.py
imports: import pytest
  import torch
  import torch.nn
  from torch import Tensor
label_desc: Use image node_id 2 for calling the MockDiffBackbone obj's underlying member method code with example usage: obj.forward(image1, image2) and returns: unknown