anchor.diff:  
   stdenv.mkDerivation rec {
     name = "vapoursynth-${version}";
  -  version = "R40";
  +  version = "R43";
   
     src = fetchFromGitHub {
       owner  = "vapoursynth";
       repo   = "vapoursynth";
       rev    = version;
  -    sha256 = "1ycc3fdhhryp7hap80z3qmh89br31kcswzp8ai3wlc07zfvcrfck";
  +    sha256 = "01yzxggjxr6fz3wj81z6vgp9m4jqddyk73i22kz2x620cpdgb9j9";
     };
   
     nativeBuildInputs = [ pkgconfig autoreconfHook nasm ];
  
positive.code: { stdenv, fetchFromGitHub, pkgconfig, autoreconfHook
  , zimg, libass, python3, libiconv
  , ApplicationServices, nasm
  , ocrSupport ?  false, tesseract
  , imwriSupport? true,  imagemagick7
  }:
  
  assert ocrSupport   -> tesseract != null;
  
negative.code:     description = "A video processing framework with the future in mind";
      homepage    = http://www.vapoursynth.com/;
      license     = licenses.lgpl21;
      platforms   = platforms.x86_64;
      maintainers = with maintainers; [ rnhmjoj ];
    };
  
  