anchor.diff:      echo "manylinux1_compatible=False" >> $out/lib/${libPrefix}/_manylinux.py
     '';
   
  +  postFixup = ''
  +    # Get rid of retained dependencies on -dev packages, and remove
  +    # some $TMPDIR references to improve binary reproducibility.
  +    for i in $out/lib/python${majorVersion}/_sysconfigdata.py $out/lib/python${majorVersion}/config-${majorVersion}m/Makefile; do
  +      sed -i $i -e "s|-I/nix/store/[^ ']*||g" -e "s|-L/nix/store/[^ ']*||g" -e "s|$TMPDIR|/no-such-path|g"
  +    done
  +
  +    # FIXME: should regenerate this.
  +    rm $out/lib/python${majorVersion}/__pycache__/_sysconfigdata.cpython*
  +
  +    # tkinter goes in a separate output
  +    mkdir -p $tkinter/${sitePackages}
  +    mv $out/lib/${libPrefix}/lib-dynload/_tkinter* $tkinter/${sitePackages}/
  +  '';
  +
  +  outputs = ["out" "tkinter"];
  +
     passthru = rec {
  -    inherit libPrefix;
  +    inherit libPrefix sitePackages;
       zlibSupport = zlib != null;
       sqliteSupport = sqlite != null;
       dbSupport = db != null;
  
positive.code:     isPy3 = true;
      isPy33 = true;
      is_py3k = true;  # deprecated
      sitePackages = "lib/${libPrefix}/site-packages";
      interpreter = "${self}/bin/${executable}";
    };
  
  
negative.code:   pythonVersion = majorVersion;
    version = "${majorVersion}.${minorVersion}${minorVersionSuffix}";
    libPrefix = "python${majorVersion}";
    sitePackages = "lib/${libPrefix}/site-packages";
  
    buildInputs = filter (p: p != null) [
      zlib bzip2 lzma gdbm sqlite db readline ncurses openssl tcl tk libX11 xproto
  