Where is the Backward function defined in PyTorch?
Backward function is same for all type of layers.
Look at 155 number line here.
https://github.com/pytorch/pytorch/blob/35bd2b3c8b64d594d85fc740e94c30aa67892a34/torch/tensor.py
and it will forward you to here
https://github.com/pytorch/pytorch/blob/35bd2b3c8b64d594d85fc740e94c30aa67892a34/torch/autograd/__init__.py