anchor.diff:        fetchurl {
           url = "https://dl.google.com/dl/cloudsdk/channels/rapid/downloads/${name}-linux-x86.tar.gz";
           sha256 = "1z2v4bg743qkdlmyyy0z2j5s0g10vbc1643gxrhyz491sk6sp616";
  +      }
  +    else if stdenv.system == "x86_64-darwin" then
  +      fetchurl {
  +        url = "https://dl.google.com/dl/cloudsdk/channels/rapid/downloads/${name}-darwin-x86_64.tar.gz";
  +        sha256 = "efbe2074da5a544c09b6bf87a8ca045dc429ac38dfcd5380561987769491d5ba";
         }
       else
         fetchurl {
  
positive.code: with python27Packages;
  
  # other systems not supported yet
  assert stdenv.system == "i686-linux" || stdenv.system == "x86_64-linux";
  
  stdenv.mkDerivation rec {
    name = "google-cloud-sdk-${version}";
  
negative.code:     license = licenses.free;
      homepage = "https://cloud.google.com/sdk/";
      maintainers = with maintainers; [stephenmw zimbatm];
      platforms = with platforms; linux ++ darwin;
    };
  }
  