anchor.diff:  
   buildPythonPackage rec {
     pname = "dotnetcore2";
  -  version = "2.1.11";
  +  version = "2.1.13";
     format = "wheel";
     disabled = isPy27;
   
  
positive.code:     inherit pname version format;
      python = "py3";
      platform = "manylinux1_x86_64";
      sha256 = "0qhp94bjz4icz2f0fnhgck875chiqzy4lvsp6lwhj5jd0zsv2bb3";
    };
  
    nativeBuildInputs = [ unzip ];
  
negative.code:     )
    ];
  
    # prevent exposing a broken dotnet executable
    postInstall = ''
      rm -r $out/${python.sitePackages}/${pname}/bin
    '';
  
    # no tests, ensure it's one useful function works
  