anchor.diff:    version = "8.2";
   in
   
  -assert pythonSupport -> python != null;
  +assert pythonSupport -> python3 != null;
   
   stdenv.mkDerivation rec {
     name =
  
positive.code: # Run time
  , ncurses, readline, gmp, mpfr, expat, zlib, dejagnu
  
  , pythonSupport ? stdenv.hostPlatform == stdenv.buildPlatform && !stdenv.hostPlatform.isCygwin, python ? null
  , guile ? null
  
  }:
  
negative.code:   nativeBuildInputs = [ pkgconfig texinfo perl setupDebugInfoDirs ];
  
    buildInputs = [ ncurses readline gmp mpfr expat zlib guile ]
      ++ stdenv.lib.optional pythonSupport python3
      ++ stdenv.lib.optional doCheck dejagnu;
  
    propagatedNativeBuildInputs = [ setupDebugInfoDirs ];
  