anchor.diff:                   qttools
                    qtsvg
                    exiv2
  -                 opencv
  +                 opencv4
                    libraw
                    libtiff
                    quazip];
  
positive.code: { stdenv
  , mkDerivation
  , fetchFromGitHub
  , cmake
  , pkgconfig
  
  
negative.code: , qtsvg
  
  , exiv2
  , opencv4
  , libraw
  , libtiff
  , quazip
  