anchor.diff:  
     config =
       let
  -      units = mapAttrs' (n: v: nameValuePair "${n}.nspawn" (instanceToUnit n v)) cfg.instances;
  +      units = mapAttrs' (n: v: nameValuePair "${n}.nspawn" (instanceToUnit n v)) cfg;
       in mkIf (cfg != {}) {
   
         environment.etc."systemd/nspawn".source = generateUnits "nspawn" units [] [];
  
positive.code:   };
  
    instanceToUnit = name: def:
      { text = ''
        [Exec]
        ${attrsToSection def.execConfig}
  
        [Files]
        ${attrsToSection def.filesConfig}
  
        [Network]
        ${attrsToSection def.networkConfig}
      '';
      };
  
  in {
  
  
negative.code:   ];
  
    instanceOptions = {
      options = sharedOptions // {
        execConfig = mkOption {
          default = {};
          example = { Parameters = "/bin/sh"; };
  