How to get the real conv2d function definition in Python

I am trying to understand how conv2d is actually invoked, e.g. the exact code for passing the arguments from Python to C++. I know that the source code for Conv2d is implemented in C++ here:

Also, I assume that the torch.nn.functional.conv2d is should be defined somewhere in Python. However, by searching “def conv2d(” doesn’t give me satisfactory results:
(1) torch/nn/quantized/, which is actually the quantization version of conv2d.
(2) torch/onnx/ doesn’t not seem to be correct either.
(3) torch/onnx/ seems to be for onnx/caffe.
Can anyone help me find the real definition in Python code for conv2d(not Module/Class, but function), and explains the stack trace for running conv2d, from Python to C++? Much appreciated!