anchor.diff:    # docker run -it --rm nix nix-store -qR $(nix-build '<nixpkgs>' -A nix)
     nix = buildImageWithNixDb {
       name = "nix";
  +    tag = "latest";
       contents = [
         # nix-store uses cat program to display results as specified by
         # the image env variable NIX_PAGER.
  
positive.code:   # dockerTools chain.
    onTopOfPulledImage = buildImage {
      name = "onTopOfPulledImage";
      fromImage = nixFromDockerHub;
      contents = [ pkgs.hello ];
    };
  
negative.code:   # 1. basic example
    bash = buildImage {
      name = "bash";
      tag = "latest";
      contents = pkgs.bashInteractive;
    };
  
  