anchor.diff:    inherit (pkgs) stdenvNoCC;
   
     cfg = config.system;
  +
  +  failedAssertions = map (x: x.message) (filter (x: !x.assertion) config.assertions);
  +
  +
  +  throwAssertions = res: if (failedAssertions != []) then throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failedAssertions)}" else res;
  +  showWarnings = res: fold (w: x: builtins.trace "[1;31mwarning: ${w}[0m" x) res config.warnings;
   
   in
   
  
positive.code:       default = pkgs.lib.nixpkgsVersion;
      };
  
    };
  
    config = {
  
      system.build.toplevel = stdenvNoCC.mkDerivation {
        name = "darwin-system-${cfg.darwinLabel}";
        preferLocalBuild = true;
  
  
negative.code:         echo -n "$darwinLabel" > $out/darwin-version
          echo -n "$system" > $out/system
        '';
      }));
  
    };
  }
  