anchor.diff:        addToSearchPath ERL_LIBS "$1/lib/erlang/lib"
       '';
   
  -    nativeBuildInputs = [ elixir hex ];
  +    buildInputs = buildInputs ++ [ ];
  +    nativeBuildInputs = nativeBuildInputs ++ [ elixir hex ];
       propagatedBuildInputs = propagatedBuildInputs ++ beamDeps;
   
       buildPhase = attrs.buildPhase or ''
  
positive.code: 
    pkg = self: stdenv.mkDerivation (attrs // {
      name = "${name}-${version}";
      inherit version src buildInputs;
  
      MIX_ENV = mixEnv;
      MIX_DEBUG = if enableDebugInfo then 1 else 0;
  
negative.code: , version
  , src
  , buildInputs ? [ ]
  , nativeBuildInputs ? [ ]
  , beamDeps ? [ ]
  , propagatedBuildInputs ? [ ]
  , postPatch ? ""
  