anchor.diff:    system.keyboard.remapCapsLockToControl = true;
   
     environment.systemPackages =
  -    [ pkgs.brotli
  +    [ config.programs.vim.package
  +      config.services.chunkwm.package
  +
  +      pkgs.brotli
         pkgs.ctags
         pkgs.curl
         pkgs.direnv
  
positive.code:       pkgs.darwin-zsh-completions
      ];
  
    services.khd.enable = true;
    services.kwm.enable = true;
    services.skhd.enable = true;
  
    launchd.user.agents.fetch-nixpkgs = {
  
negative.code:           EOF
          '';
  
        # Fake package, not in nixpkgs.
        chunkwm = super.runCommandNoCC "chunkwm-0.0.0" {} ''
          mkdir $out
        '';
  
        vim_configurable = super.vim_configurable.override {
          guiSupport = "no";
        };
      })
    ];
  
    # Dotfiles.
    # nixpkgs.overlays = mkAfter [ (import <dotpkgs/overlays/50-trivial-packages.nix>) ];
  
    services.khd.khdConfig = ''
      # modifier only mappings
  