anchor.diff:      "-DEIGEN3_INCLUDE_DIR=${eigen}/include/eigen3"
       "-DRDK_INSTALL_INTREE=OFF"
       "-DRDK_INSTALL_STATIC_LIBS=OFF"
  +    "-DRDK_INSTALL_COMIC_FONTS=OFF"
       "-DRDK_BUILD_INCHI_SUPPORT=ON"
       "-DRDK_BUILD_AVALON_SUPPORT=ON"
       "-DRDK_BUILD_FREESASA_SUPPORT=ON"
  
positive.code:     yaehmop = fetchFromGitHub {
        owner = "greglandrum";
        repo = "yaehmop";
        rev = "1b13b52e2738a77715b1bad876e3b4e93f2b5269";
        sha256 = "1jp7wz8win4mgwxkaz2gnrgsaaqgln04n2lwgfr96isdv1klf62d";
      };
      freesasa = fetchFromGitHub
        {
          owner = "mittinatten";
          repo = "freesasa";
          rev = "2.0.3";
          sha256 = "0x686zm9fpyg5647fdgxnxgbwav99nc6ymh4bmkr2063yyda4kzc";
        };
    };
  in
  buildPythonPackage rec {
    pname = "rdkit";
    version = "2020.09.5";
  
    src =
      let
  
negative.code:       owner = pname;
        repo = pname;
        rev = "Release_${versionTag}";
        sha256 = "sha256-YZq1JKDlCQVvjv7+XpEhD/wfFcQ5m3i5VO4rNQ3ONRQ=";
      };
  
    unpackPhase = ''
  