anchor.diff:  
         script = ''
           ${pkgs.docker-distribution}/bin/registry serve \
  -          ${pkgs.docker-distribution.out}/share/go/src/github.com/docker/distribution/cmd/registry/config-example.yml
  +          /etc/docker/registry/config.yml
         '';
   
         serviceConfig = {
  
positive.code: 
  let
    cfg = config.services.dockerRegistry;
  
  in {
    options.services.dockerRegistry = {
  
negative.code:   };
  
    config = mkIf cfg.enable {
      environment.etc."docker/registry/config.yml".text = builtins.toJSON registryConfig;
  
      systemd.services.docker-registry = {
        description = "Docker Container Registry";
        wantedBy = [ "multi-user.target" ];
  