anchor.diff:  # https://storage.googleapis.com/jax-releases/libtpu_releases.html.
   
   # For future reference, the easiest way to test the GPU backend is to run
  -#   NIX_PATH=.. nix-shell -p python3 python3Packages.jax "python3Packages.jaxlib.override { cudaSupport = true; }"
  +#   NIX_PATH=.. nix-shell -p python3 python3Packages.jax "python3Packages.jaxlib-bin.override { cudaSupport = true; }"
   #   export XLA_FLAGS=--xla_gpu_force_compilation_parallelism=1
   #   python -c "from jax.lib import xla_bridge; assert xla_bridge.get_backend().platform == 'gpu'"
   #   python -c "from jax import random; random.PRNGKey(0)"
  
positive.code:     sourceProvenance = with sourceTypes; [ binaryNativeCode ];
      license = licenses.asl20;
      maintainers = with maintainers; [ samuela ];
      platforms = [ "x86_64-linux" ];
    };
  }
  
negative.code:   inherit version;
    format = "wheel";
  
    # At the time of writing (2022-10-19), there are releases for <=3.10.
    # Supporting all of them is a pain, so we focus on 3.10, the current nixpkgs
    # python version.
    disabled = !(pythonVersion == "3.10");
  
    src = if !cudaSupport then cpuSrcs."${stdenv.hostPlatform.system}" else gpuSrc;
  
    # Prebuilt wheels are dynamically linked against things that nix can't find.
    # Run `autoPatchelfHook` to automagically fix them.
    nativeBuildInputs = lib.optionals cudaSupport [ autoPatchelfHook addOpenGLRunpath ];
    # Dynamic link dependencies
    buildInputs = [ stdenv.cc.cc ];
  
  