anchor.diff:  , cmake
   , pkg-config
   , makeWrapper
  +, fftw
   , fmt_8
   , libsndfile
  +, rtmidi
   , SDL2
   , zlib
   , withJACK ? stdenv.hostPlatform.isUnix
  
positive.code:     };
      tests.version = testers.testVersion {
        package = furnace;
        # The command always exits with code 1
        command = "(furnace --version || [ $? -eq 1 ])";
      };
    };
  
  
negative.code: 
  stdenv.mkDerivation rec {
    pname = "furnace";
    version = "0.6pre1";
  
    src = fetchFromGitHub {
      owner = "tildearrow";
      repo = "furnace";
      rev = "v${version}";
      fetchSubmodules = true;
      sha256 = "sha256-7MrzSC8PYQ4X8fyX1hB8mOoSCtLpY+o1x42v9HLdoao=";
    };
  
    nativeBuildInputs = [
      cmake
  