anchor.diff:  
     src = fetchurl {
       url = "mirror://sourceforge/flightgear/release-${shortVersion}/${pname}-${version}.tar.bz2";
  -    sha256 = "1770kgwa7z70sx6da9x1q9cszpd3ywz6nn8jrb6xv8ldjqcpqpvb";
  +    sha256 = "02d9h10p8hyn0a25csragj6pbwmrir1z8zb92023s9vi21j7bwy8";
     };
   
     # Of all the files in the source and data archives, there doesn't seem to be
  
positive.code: 
      src = fetchurl {
        url = "mirror://sourceforge/flightgear/release-${shortVersion}/FlightGear-${version}-data.tar.bz2";
        sha256 = "0ldsjb54k8nb99h6n4f4x20nawd2pa0a8skkwkrgckdpmdv0zwyk";
      };
  
      phases = [ "installPhase" ];
  
negative.code: }:
  
  let
    version = "2020.3.4";
    shortVersion = builtins.substring 0 6 version;
    data = stdenv.mkDerivation rec {
      pname = "flightgear-data";
  