anchor.diff:                  services.nixosManual.enable = false; # !!!
                 };
             }
  -        ) machinesWithIP;
  +          (lib.getAttr m.first nodes)
  +        ]) machinesWithIP;
   
       in lib.listToAttrs nodes_;
   
  
positive.code: 
  
    buildVM =
      nodes: configuration:
  
      import "${nixos}/lib/eval-config.nix" {
        inherit nixpkgs services system;
        modules = [ configuration ];
        extraArgs = { inherit nodes; };
        /* !!! bug in the module/option handling: this ignores the
           config from assignIPAddresses.  Too much magic. 
  
negative.code:       # Generate a /etc/hosts file.
        hosts = lib.concatMapStrings (m: "${m.second} ${m.first}\n") machinesWithIP;
  
        nodes_ = map (m: lib.nameValuePair m.first [
            { config =
                { networking.hostName = m.first;
                  networking.interfaces =
                    [ { name = "eth1";
  