lib: _: with lib; rec {
  my = import ./my.nix lib;

  dns = import ./dns.nix;

  isEven =
    number:
    assert (builtins.isInt number) || (builtins.isFloat number);
    builtins.div number 2 == 0;

  isOdd = number: !isEven number;

  pow =
    base: exponent:
    assert (builtins.isInt base) && (builtins.isInt exponent);
    assert exponent > 0;
    builtins.foldl' (x: _: x * base) 1 (builtins.genList (_: _) exponent);

  mkTcpMem =
    min: ini: max:
    assert min <= ini && ini <= max;
    concatMapStrings (x: toString x + " ") (
      map (pow 2) [
        min
        ini
        max
      ]
    );

  modulesIn =
    dir:
    pipe dir [
      builtins.readDir
      (mapAttrsToList (
        name: type:
        if type == "regular" && hasSuffix ".nix" name && name != "default.nix" then
          [
            {
              name = removeSuffix ".nix" name;
              value = dir + "/${name}";
            }
          ]
        else if type == "directory" && pathExists (dir + "/${name}/default.nix") then
          [
            {
              inherit name;
              value = dir + "/${name}";
            }
          ]
        else
          [ ]
      ))
      concatLists
      listToAttrs
    ];

  moduleFromRef = module: ref: sha256: {
    disabledModules = [ module ];
    imports = [
      (
        let
          src = builtins.fetchTarball {
            url =
              let
                cons = splitString ":" ref;
                owner = head cons;
                branch = last cons;
              in
              "https://github.com/${owner}/nixpkgs/archive/refs/heads/${branch}.tar.gz";
            inherit sha256;
          };
        in
        "${src}/nixos/modules/${module}"
      )
    ];
  };
}