anchor.diff:  
     buildInputs = builtins.attrValues ciTools;
     shellInputs = builtins.attrValues devTools;
  -  shellHook = lib.optionalString (targetAndroid) ''
  -    echo "Configuring Flutter with path to Android Studio..."
  -    ${pkgs.flutter}/bin/flutter config --android-studio-dir "${pkgs.android-studio.unwrapped}" --android-sdk=
  +  shellHook = ''
  +    export FLUTTER_SDK_ROOT=${pkgs.flutter.unwrapped}
  +    echo "Configuring Flutter..."
  +    ${flutterConfig}
       echo "Accepting Android licenses..."
       yes | ${pkgs.flutter}/bin/flutter doctor --android-licenses
     '';
  
positive.code:     exec = exec';
    };
  
    android_overlay = _: pkgs: pkgs.lib.optionalAttrs (targetAndroid) {
      androidsdk = (pkgs.androidenv.composeAndroidPackages {
        buildToolsVersions = [ "28.0.3" ];
        platformVersions = [ "29" ];
        platformToolsVersion = "29.0.6";
        includeNDK = true;
        ndkVersion = "21.0.6113669";
        abiVersions = [ "x86-64" ];
      }).androidsdk;
    };
    fix-autopatchelfhook = import sources.fix-autopatchelfhook {
      overlays = [
        android_overlay
      ];
    };
  
    flutter_overlay = _: pkgs: pkgs.lib.optionalAttrs (includeFlutter) {
      flutter = pkgs.flutterPackages.dev;
    };
  
    pkgs = import sources.nixpkgs {
      overlays = [
        (_: pkgs: { inherit (fix-autopatchelfhook) androidsdk; })
        flutter_overlay
      ];
    };
  
negative.code: # limitations under the License.
  
  { sources ? import ./sources.nix
  }:
  let
    make-extra-builtins = import sources.nix-fetchers."make-extra-builtins.nix" {};
  