nhs: 
```
let
  pytorchOverlay = curr: prev: {
    python38 = prev.python38.override {
      packageOverrides = (pyCurr: pyPrev:{
        pytorch = pyPrev.pytorch.override {
          cudatoolkit = prev.cudatoolkit_11;
        };
      });
    };
  };
  pkgs = import <unstable> { overlays = [ pytorchOverlay ]; };
in
pkgs.python38.pkgs.pytorch
```