anchor.diff:          storePaths=$(cat ${nixRegistration contents}/storePaths)
           echo "Copying everything to /nix/store (will take a while)..."
           cp -prd $storePaths nix/store/
  -        ${nixUnstable}/bin/nix-store --verify --check-contents
  +        ${nix}/bin/nix-store --verify --check-contents
   
           mkdir -p nix/var/nix/gcroots/docker/
           for i in ${lib.concatStringsSep " " contents}; do
  
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:     '';
  
    nixRegistration = contents: runCommand "nix-registration" {
      buildInputs = [ nix perl ];
      # For obtaining the closure of `contents'.
      exportReferencesGraph =
        let contentsList = if builtins.isList contents then contents else [ contents ];
  