{
  nixpkgs ?  import (builtins.fetchGit {
    url = "https://github.com/nixos/nixpkgs-channels/";

    #
    # Commit hash for nixos-unstable
    # `git ls-remote https://github.com/nixos/nixpkgs-channels nixos-unstable`
    name = "nixos-unstable-2020-07-06";
    ref = "refs/heads/nixos-unstable";
    rev = "dc80d7bc4a244120b3d766746c41c0d9c5f81dfa";

    #
    # Commit hash for nixos-20.03
    # `git ls-remote https://github.com/nixos/nixpkgs-channels nixos-20.03`
    #name = "nixos-20.03-2020-07-06";
    #ref = "refs/heads/nixos-20.03";
    #rev = "afa9ca61924f05aacfe495a7ad0fd84709d236cc";
  }) {}
}:

with nixpkgs;

let
  python = python36;
  python-with-base-packages = python.withPackages(ps: with ps; [
    # the following packages are related to the dependencies of your python
    # project.
    # In this particular example the python modules listed in the
    # requirements.txt require the following packages to be installed locally
    # in order to compile any binary extensions they may require.
    #

    scipy
  ]);

in mkShell {

  buildInputs = [
    python-with-base-packages
    python3Packages.venvShellHook
  ];

  shellHook = ''
    # set SOURCE_DATE_EPOCH so that we can use python wheels
    SOURCE_DATE_EPOCH=$(date +%s)
    venvShellHook
  '';
}