anchor.diff:      (wtFlag "boost" (boost != null) null)
       (wtFlag "boost-libdir" (boost != null) "${boost.lib}/lib")
       "--with-gettext"
  -    "--disable-tools"
  +    "--without-tools"
     ];
   
     buildPhase = ''
  
positive.code:     libmatroska
      libogg
      libvorbis
      qt5.qtbase
      xdg-utils
      zlib
    ];
  
    postPatch = ''
      patchShebangs ./rake.d/
      patchShebangs ./Rakefile
    '' +
    /* Force ruby encoding to UTF-8 or else when enabling qt5 the
       Rakefile mayfail with `invalid byte sequence in US-ASCII'
       due to UTF-8 characters. This workaround replaces an
       arbitrary comment in the drake file. */ ''
      sed -i ./drake \
        -e 's,#--,Encoding.default_external = Encoding::UTF_8,'
    '';
  
    configureFlags = [
  
negative.code: , libmatroska
  , libogg
  , libvorbis
  , pugixml
  , qt5
  , xdg-utils
  , zlib
  }:
  
  with {
  