anchor.diff:  
     passthru = {
       srcVerification = fetchurl {
  +      inherit (src)
  +        outputHash
  +        outputHashAlgo
  +        urls;
         failEarly = true;
         pgpsigUrls = map (n: "${n}.asc") src.urls;
         pgpKeyFingerprint = "D827 2EF5 1DA2 23E4 D05B  4669 89AB 63D4 8277 377A";
  -      inherit (src) urls outputHash outputHashAlgo;
       };
     };
   
  
positive.code:     "--with-modules"
      "--with-frozenpaths"
      "--with-magick-plus-plus"
      (wtFlag "perl" (perl != null) null)
      (wtFlag "perl-options" (perl != null) "PREFIX=\${out}")
      (wtFlag "jemalloc" (jemalloc != null) null)
      #(wtFlag "umem" ( != null) null)
      (wtFlag "bzlib" (bzip2 != null) null)
      (wtFlag "x" (xorg != null) null)
      (wtFlag "zlib" (zlib != null) null)
      #(wtFlag "autotrace" ( != null) null)
      #(wtFlag "dps" ( != null) null)
      (wtFlag "dejavu-font-dir" (dejavu_fonts != null)
        "${dejavu_fonts}/share/fonts/truetype/")
      (wtFlag "fftw" (fftw_single != null) null)
      (wtFlag "fpx" (libfpx != null) null)
      (wtFlag "djvu" (djvulibre != null) null)
      (wtFlag "fontconfig" (fontconfig != null) null)
      (wtFlag "freetype" (freetype != null) null)
      (wtFlag "gslib" (ghostscript != null) null)
      #(wtFlag "fontpath=" ( != null) null)
      (if (ghostscript != null) then
        "--with-gs-font-dir=${ghostscript}/share/ghostscript/fonts/"
       else
         "--without-gs-font-dir")
      (wtFlag "gvc" (graphviz != null) null)
      (wtFlag "jbig" (jbigkit != null) null)
      (wtFlag "jpeg" (libjpeg != null) null)
      (wtFlag "lcms" (lcms2 != null) null)
      (wtFlag "openjp2" (openjpeg != null) null)
      (wtFlag "lqr" (liblqr1 != null) null)
      (wtFlag "lzma" (xz != null) null)
      (wtFlag "openexr" (openexr != null) null)
      (wtFlag "pango" (pango != null) null)
      (wtFlag "png" (libpng != null) null)
      (wtFlag "rsvg" (librsvg != null) null)
      (wtFlag "tiff" (libtiff != null) null)
      (wtFlag "webp" (libwebp != null) null)
      #(wtFlag "windows-font-dir=" ( != null) null)
      #(wtFlag "wmf" ( != null) null)
      (wtFlag "xml" (libxml2 != null) null)
    ];
  
    postInstall = ''
      (cd "$out/include" && ln -s ImageMagick* ImageMagick)
    '' + stdenv.lib.optionalString (ghostscript != null) ''
      for la in $out/lib/*.la ; do
        sed -i $la \
          -e 's|-lgs|-L${ghostscript}/lib -lgs|'
  
negative.code: 
  let
    inherit (stdenv.lib)
      boolString
      boolWt
      optionalString;
  
    # Use stable patch releases, e.g. -9 or -10
    version = "7.0.2-10";
  in
  
  assert xorg != null ->
  