/**
  Collection of locally provided Python packages.

  Add packages by creating a directory containing a `default.nix` file.
  The directory name will be used for the attribute name in package set.

  A package crecipe can use Python packages in its argument directly, e.g.

  ```nix
  { fetchFromGitHub, buildPythonPackage, django_4 }:
  {
    # ...
  }
  ```
*/
{ pkgs }:
let
  callPackage = pkgs.lib.callPackageWith (pkgs // pkgs.python3.pkgs // extraPython3Packages);

  extraPython3Packages =
    let
      dir = builtins.path {
        path = ./.;
        name = "source";
      };
    in
    with builtins;
    listToAttrs (
      map (name: {
        inherit name;
        value = callPackage (dir + "/${name}") { };
      }) (attrNames (readDir dir))
    );
in
extraPython3Packages