anchor.diff:      ln -s "$out/bin/python3" "$out/bin/python"
       ln -s "$out/bin/python3-config" "$out/bin/python-config"
       ln -s "$out/lib/pkgconfig/python3.pc" "$out/lib/pkgconfig/python.pc"
  +
  +    # Determinism: rebuild all bytecode
  +    # We exclude lib2to3 because that's Python 2 code which fails
  +    # We rebuild three times, once for each optimization level
  +    find $out -name "*.py" | $out/bin/python -m compileall -q -f -x "lib2to3" -i -
  +    find $out -name "*.py" | $out/bin/python -O -m compileall -q -f -x "lib2to3" -i -
  +    find $out -name "*.py" | $out/bin/python -OO -m compileall -q -f -x "lib2to3" -i -
     '';
   
     passthru = let
  
positive.code: 
    NIX_LDFLAGS = optionalString stdenv.isLinux "-lgcc_s";
  
    prePatch = optionalString stdenv.isDarwin ''
      substituteInPlace configure --replace '`/usr/bin/arch`' '"i386"'
      substituteInPlace configure --replace '-Wl,-stack_size,1000000' ' '
  
negative.code:     })
    ];
  
    postPatch = ''
      # Determinism
      substituteInPlace "Lib/py_compile.py" --replace "source_stats['mtime']" "(1 if 'DETERMINISTIC_BUILD' in os.environ else source_stats['mtime'])"
      # Determinism. This is done unconditionally
      substituteInPlace "Lib/importlib/_bootstrap_external.py" --replace "source_mtime = int(st['mtime'])" "source_mtime = 1"
    '' + optionalString (x11Support && (tix != null)) ''
      substituteInPlace "Lib/tkinter/tix.py" --replace "os.environ.get('TIX_LIBRARY')" "os.environ.get('TIX_LIBRARY') or '${tix}/lib'"
    '';
  
    CPPFLAGS="${concatStringsSep " " (map (p: "-I${getDev p}/include") buildInputs)}";
    LDFLAGS="${concatStringsSep " " (map (p: "-L${getLib p}/lib") buildInputs)}";
    LIBS="${optionalString (!stdenv.isDarwin) "-lcrypt"} ${optionalString (ncurses != null) "-lncurses"}";
  
    configureFlags = [
      "--enable-shared"
      "--with-threads"
      "--without-ensurepip"
    ];
  
    preConfigure = ''
      for i in /usr /sw /opt /pkg; do	# improve purity
  