anchor.diff:      mkdir -p $out
       cp -R * $out/
       echo $libPath
  -  '' + lib.optionalString(stdenv.isLinux) ''
  +  '' + lib.optionalString (stdenv.isLinux) ''
       find $out/bin -executable -type f -exec patchelf --set-interpreter $(cat $NIX_CC/nix-support/dynamic-linker) {} \;
     '';
   
  
positive.code: , lib
  , fetchurl
  , unzip
  , version ? "2.17.3"
  , sources ? let
      base = "https://storage.googleapis.com/dart-archive/channels";
      x86_64 = "x64";
  
negative.code:     aarch64 = "arm64";
      # Make sure that if the user overrides version parameter they're
      # also need to override sources, to avoid mistakes
      version = "2.18.0";
    in
    {
      "${version}-aarch64-darwin" = fetchurl {
        url = "${base}/stable/release/${version}/sdk/dartsdk-macos-${aarch64}-release.zip";
        sha256 = "sha256-wfUh6rXy8jAC0TVQJzXh4SrV2DQs9SvY8PGtNgZx+cA=";
      };
      "${version}-x86_64-darwin" = fetchurl {
        url = "${base}/stable/release/${version}/sdk/dartsdk-macos-${x86_64}-release.zip";
        sha256 = "sha256-zyu6r8akId/AHpBKH95wJXXu1LD9CKShWYKfppnSRx4=";
      };
      "${version}-x86_64-linux" = fetchurl {
        url = "${base}/stable/release/${version}/sdk/dartsdk-linux-${x86_64}-release.zip";
        sha256 = "sha256-45HE7Y9iO5dI+JfLWF1ikFfBFB+er46bK+EYkyuhFjI=";
      };
      "${version}-i686-linux" = fetchurl {
        url = "${base}/stable/release/${version}/sdk/dartsdk-linux-${i686}-release.zip";
        sha256 = "sha256-IkSJWfAocT1l8F2igAkR+Y5PNYD5PZ0j21D8aJk9JCY=";
      };
      "${version}-aarch64-linux" = fetchurl {
        url = "${base}/stable/release/${version}/sdk/dartsdk-linux-${aarch64}-release.zip";
        sha256 = "sha256-Bt18brbJA/XfiyP5o197HDXMuGm+a1AZx92Thoriv78=";
      };
    }
  }:
  