anchor.diff:    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
  
positive.code:     isPy3 = true;
      isPy33 = true;
      is_py3k = true;  # deprecated
      sitePackages = "lib/${libPrefix}/site-packages";
      interpreter = "${self}/bin/${executable}";
    };
  
  
negative.code:     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 sitePackages;
      zlibSupport = zlib != null;
      sqliteSupport = sqlite != null;
      dbSupport = db != null;
  