anchor.diff:      nlopt
       lp_solve
       colpack
  -  ] ++ lib.optionals pythonSupport (with python2Packages; [ python numpy ])
  +  ] ++ lib.optionals pythonSupport (with python3Packages; [ python numpy ])
       ++ lib.optional opencvSupport opencv;
   
     cmakeFlags = let
  
positive.code:     "-DENABLE_TESTING=${enableIf doCheck}"
      "-DDISABLE_META_INTEGRATION_TESTS=ON"
      "-DTRAVIS_DISABLE_META_CPP=ON"
      "-DPythonModular=${enableIf pythonSupport}"
      "-DOpenCV=${enableIf opencvSupport}"
      "-DUSE_SVMLIGHT=${enableIf withSvmLight}"
    ];
  
negative.code:   ] ++ lib.optional (!withSvmLight) ./svmlight-scrubber.patch;
  
    nativeBuildInputs = [ cmake swig ctags ]
      ++ (with python3Packages; [ python jinja2 ply ]);
  
    buildInputs = [
      eigen
  