anchor.diff:      ++ optionals stdenv.isDarwin [ CF configd ];
   
     hasDistutilsCxxPatch = !(stdenv.cc.isGNU or false);
  -
  +  pythonForBuild = if stdenv.hostPlatform == stdenv.buildPlatform then
  +    "$out/bin/python"
  +  else
  +    buildPackages.python37.interpreter;
   in stdenv.mkDerivation {
     name = "python3-${version}";
     pythonVersion = majorVersion;
     inherit majorVersion version;
   
     inherit buildInputs;
  +
  +  nativeBuildInputs =
  +    optionals (stdenv.hostPlatform != stdenv.buildPlatform)
  +    [ buildPackages.stdenv.cc buildPackages.python37 ];
   
     src = fetchurl {
       url = "https://www.python.org/ftp/python/${majorVersion}.${minorVersion}/Python-${version}.tar.xz";
  
positive.code:     "--with-system-expat"
      "--with-system-ffi"
      "--with-openssl=${openssl.dev}"
    ];
  
    preConfigure = ''
  
negative.code:     # We rebuild three times, once for each optimization level
      # Python 3.7 implements PEP 552, introducing support for deterministic bytecode.
      # This is automatically used when `SOURCE_DATE_EPOCH` is set.
      find $out -name "*.py" | ${pythonForBuild}     -m compileall -q -f -x "lib2to3" -i -
      find $out -name "*.py" | ${pythonForBuild} -O  -m compileall -q -f -x "lib2to3" -i -
      find $out -name "*.py" | ${pythonForBuild} -OO -m compileall -q -f -x "lib2to3" -i -
    '';
  
    passthru = let
  