anchor.diff:  { config, stdenv, fetchurl, fetchFromGitHub, makeWrapper
  -, addOpenGLRunpath, docutils, perl, pkgconfig, python3, which
  +, addOpenGLRunpath, docutils, perl, pkgconfig, python3, wafHook, which
   , ffmpeg_4, freefont_ttf, freetype, libass, libpthreadstubs, mujs
   , nv-codec-headers, lua, libuchardet, libiconv ? null, darwin
   
  
positive.code: 
    enableParallelBuilding = true;
  
    buildPhase = ''
      python3 ${waf} build
    '' + optionalString stdenv.isDarwin ''
      python3 TOOLS/osxbundle.py -s build/mpv
    '';
  
  
negative.code:       --prefix PYTHONPATH : "${vapoursynth}/lib/${python3.libPrefix}/site-packages:$PYTHONPATH"
    '';
  
    postInstall = ''
      # Use a standard font
      mkdir -p $out/share/mpv
      ln -s ${freefont_ttf}/share/fonts/truetype/FreeSans.ttf $out/share/mpv/subfont.ttf
  