{
  config,
  lib,
  pkgs,
  ...
}:
{
  options.my.apps.piano.enable = lib.mkEnableOption "piano learning and music theory apps";
  config = lib.mkIf config.my.apps.piano.enable {
    users.users = let
      users = if lib.isString config.my.toggleUsers.apps then [ config.my.toggleUsers.apps ] else config.my.toggleUsers.apps;
      packages = builtins.attrValues {
      inherit (pkgs)
        neothesia
        linthesia
        timidity
        ;
      };
    in lib.mkMerge (map (user: {
        ${user}.packages = packages;
      }) users);
  };
}