anchor.diff:      "--enable-glibtest"
       "--enable-nls"
       "--enable-rpath"
  -    (enFlag "introspection" (gobject-introspection != null) null)
  +    "--${boolEn (gobject-introspection != null)}-introspection"
       "--disable-gtk-doc"
       "--disable-gtk-doc-html"
       "--disable-gtk-doc-pdf"
     ];
   
     postInstall = "rm -rvf $out/share/gtk-doc";
  +
  +  passthru = {
  +    srcVerification = fetchurl {
  +      inherit (src)
  +        outputHash
  +        outputHashAlgo
  +        urls;
  +      sha256Url = "https://download.gnome.org/sources/atk/"
  +        + "${channel}/${name}.sha256sum";
  +      failEarly = true;
  +    };
  +  };
   
     meta = with stdenv.lib; {
       description = "GTK+ & GNOME Accessibility Toolkit";
  
positive.code: 
  let
    inherit (stdenv.lib)
      enFlag;
  
    source = (import ./sources.nix { })."${channel}";
  in
  
negative.code: 
    src = fetchurl {
      url = "mirror://gnome/sources/atk/${channel}/${name}.tar.xz";
      hashOutput = false;
      inherit (source) sha256;
    };
  
  