anchor.diff:    installFlags = stdenv.lib.optionalString (stdenv.system == "x86_64-linux")
       "prefix=$(out)";
     patchPhase = stdenv.lib.optionalString (stdenv.system == "x86_64-linux")
  -    "sed -i 's/ldconfig//' Makefile";
  +    "${gnused}/bin/sed -i 's/ldconfig//' Makefile";
     postInstall = stdenv.lib.optionalString (stdenv.system == "x86_64-linux")
       "mv -v share $out";
   
  
positive.code:   # common
    buildPhase = "true";
    # no patch or build phase for darwin
    phases = [ "unpackPhase" "installPhase" ]
      ++ stdenv.lib.optionals (stdenv.system == "x86_64-linux")
        [ "patchPhase" "buildPhase" ];
    installPhase = if (stdenv.system == "x86_64-linux")
      then "installPhase"
      else ''
  
negative.code: { stdenv, fetchurl, libspotify, alsaLib, readline, pkgconfig, apiKey, unzip, gnused }:
  
  let version = "12.1.51"; in
  
  if (stdenv.system != "x86_64-linux" && stdenv.system != "x86_64-darwin")
  then throw "Check https://developer.spotify.com/technologies/libspotify/ for a tarball for your system and add it here"
  else stdenv.mkDerivation {
    name = "libspotify-${version}";
  