Operators call and dispatch (binding)

Currently I understand most of the torch operators are registered in native_functions.yaml. With their implementations in folders like aten/src/Aten/native/, aten/src/Aten/native/cpu/ and aten/src/Aten/native/cuda* .

But I am still confused about HOW exactly PyTorch calls its own operators.

Now I have an image like this, which is from website.
!https://upload-images.jianshu.io/upload_images/13575947-68ee8c4b75723454.png?imageMogr2/auto-orient/strip|imageView2/2/w/1240

Could anybody please show the specific code that are doing these dispatching things?