anchor.diff:          ++ lib.optionals (!is20) [ curl perl ]
           ++ lib.optionals fromGit [ autoreconfHook autoconf-archive bison flex libxml2 libxslt docbook5 docbook_xsl_ns jq ];
   
  -      buildInputs = [ curl openssl sqlite xz bzip2 ]
  +      buildInputs = [ curl openssl sqlite xz bzip2 nlohmann_json ]
           ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
           ++ lib.optionals is20 [ brotli boost editline ]
           ++ lib.optional withLibseccomp libseccomp
  
positive.code: 
  common =
    { lib, stdenv, fetchpatch, perl, curl, bzip2, sqlite, openssl ? null, xz
    , pkgconfig, boehmgc, perlPackages, libsodium, brotli, boost, editline
    , autoreconfHook, autoconf-archive, bison, flex, libxml2, libxslt, docbook5, docbook_xsl_ns, jq
    , busybox-sandbox-shell
    , storeDir
  
negative.code: 
    nixFlakes = lib.lowPrio (callPackage common rec {
      name = "nix-2.4${suffix}";
      suffix = "pre20191022_9cac895";
      src = fetchFromGitHub {
        owner = "NixOS";
        repo = "nix";
        rev = "9cac895406724e0304dff140379783c4d786e855";
        hash = "sha256-Y1cdnCNoJmjqyC/a+Nt2N+5L3Ttg7K7zOD7gmtg1QzA=";
      };
      fromGit = true;
  
  