anchor.diff: -{ lib, stdenv
  +{ lib
  +, stdenv
   , fetchurl
   , autoPatchelfHook
   , fixDarwinDylibNames
  
positive.code:     ++ optional stdenv.isLinux autoPatchelfHook
      ++ optional stdenv.isDarwin fixDarwinDylibNames;
  
    outputs = [ "out" "dev" "lib"];
  
    unpackCmd = "unzip $curSrc";
  
  
negative.code:     license = licenses.unfree;
      platforms = [ "x86_64-linux" "x86_64-darwin" ];
      maintainers = with maintainers; [ flokli ];
      hydraPlatforms = [ ];
    };
  }
  