anchor.diff:  
   let
   
  +  majorVersion = "2.6";
  +  version = "${majorVersion}.4";
  +
     buildInputs =
       optional (stdenv ? gcc && stdenv.gcc.libc != null) stdenv.gcc.libc ++
       [bzip2]
  
positive.code:   inherit buildInputs;
    C_INCLUDE_PATH = concatStringsSep ":" (map (p: "${p}/include") buildInputs);
    LIBRARY_PATH = concatStringsSep ":" (map (p: "${p}/lib") buildInputs);
    configureFlags = ''${if stdenv.isDarwin then "" else " --enable-shared"} --with-wctype-functions'';
  
    preConfigure = ''
      # Purity.
  
negative.code:   setupHook = ./setup-hook.sh;
  
    postInstall = ''
      rm -rf "$out/lib/python${majorVersion}/test"
    '';
  
    passthru = {
  