anchor.diff:    buildInputs = [ boost ]
       ++ stdenv.lib.optionals z3Support [ z3 ]
       ++ stdenv.lib.optionals cvc4Support [ cvc4 cln gmp ];
  -  checkInputs = [ ncurses python2 ];
  +  checkInputs = [ ncurses python3 ];
   
     # Test fails on darwin for unclear reason
     doCheck = stdenv.hostPlatform.isLinux;
  
positive.code: stdenv.mkDerivation rec {
  
    pname = "solc";
    version = "0.5.15";
  
    # upstream suggests avoid using archive generated by github
    src = fetchzip {
      url = "https://github.com/ethereum/solidity/releases/download/v${version}/solidity_${version}.tar.gz";
      sha256 = "1nfvsaci5ja5ss603z04197wndwkvcq9nm5mdab1kpdr91djxh2y";
    };
  
    postPatch = ''
  
negative.code:     pushd ..
      # IPC tests need aleth avaliable, so we disable it
      sed -i "s/IPC_ENABLED=true/IPC_ENABLED=false\nIPC_FLAGS=\"--no-ipc\"/" ./scripts/tests.sh
      for i in ./scripts/*.sh ./scripts/*.py ./test/*.sh; do
        patchShebangs "$i"
      done
      TERM=xterm ./scripts/tests.sh
  