nixpkgs/pkgs/development/tools/build-managers/rake/gemset.nix

{
  rake = {
    groups = ["default"];
    platforms = [];
    source = {
      remotes = ["https://rubygems.org"];
      sha256 = "1sy5a7nh6xjdc9yhcw31jji7ssrf9v5806hn95gbrzr998a2ydjn";
      type = "gem";
    };
    version = "12.3.2";
  };
}