anchor.diff:      '';
   
     nixRegistration = contents: runCommand "nix-registration" {
  -    buildInputs = [ nixUnstable perl ];
  +    buildInputs = [ nix perl ];
       # For obtaining the closure of `contents'.
       exportReferencesGraph =
         let contentsList = if builtins.isList contents then contents else [ contents ];
  
positive.code:         echo "         be better to only have one layer that contains a nix store."
          # This requires Nix 1.12 or higher
          export NIX_REMOTE=local?root=$PWD
          ${nixUnstable}/bin/nix-store --load-db < ${nixRegistration contents}/db.dump
  
          # We fill the store in order to run the 'verify' command that
          # generates hash and size of output paths.
  
negative.code:   lib,
    pkgs,
    pigz,
    nix,
    perl,
    runCommand,
    rsync,
  