anchor.diff:  let
     # js/css assets that setup.py tries to fetch via `npm install` when building
     # from source.
  -  bootstrap = 
  +  bootstrap =
       fetchzip {
         url = "https://registry.npmjs.org/bootstrap/-/bootstrap-3.3.7.tgz";
         sha256 = "0r7s54bbf68ri1na9bbabyf12mcpb6zk5ja2q6z82aw1fa4xi3yd";
       };
  -  font-awesome = 
  +  font-awesome =
       fetchzip {
         url = "https://registry.npmjs.org/font-awesome/-/font-awesome-4.7.0.tgz";
         sha256 = "1xnxbdlfdd60z5ix152m8r2kk9dkwlqwpypky1mm3dv64ajnzdbk";
       };
  -  jquery = 
  +  jquery =
       fetchzip {
         url = "https://registry.npmjs.org/jquery/-/jquery-3.2.1.tgz";
         sha256 = "1j6y18miwzafdj8kfpwbmbn9qvgnbnpc7l4arqrhqj33m04xrlgi";
       };
  -  moment = 
  +  moment =
       fetchzip {
  -      url = "https://registry.npmjs.org/moment/-/moment-2.18.1.tgz";
  -      sha256 = "1b4vyvs24v6y92pf2iqjm5aa7jg7khcpspn00girc7lpi917f9vw";
  +      url = "https://registry.npmjs.org/moment/-/moment-2.22.2.tgz";
  +      sha256 = "12gb3p0rz5wyjwykv9g0pix7dd352lx1z7rzdjsf2brhwc4ffyip";
       };
  -  requirejs = 
  +  requirejs =
       fetchzip {
         url = "https://registry.npmjs.org/requirejs/-/requirejs-2.3.4.tgz";
         sha256 = "0q6mkj0iv341kks06dya6lfs2kdw0n6vc7n4a7aa3ia530fk9vja";
  
positive.code: 
  buildPythonPackage rec {
    pname = "jupyterhub";
    version = "0.8.1";
  
    src = fetchPypi {
      inherit pname version;
      sha256 = "100cf18d539802807a45450d38fefbb376cf1c810f3b1b31be31638829a5c69c";
    };
  
    # Most of this only applies when building from source (e.g. js/css assets are
  
negative.code: 
    propagatedBuildInputs = [
      alembic ipython jinja2 pamela python-oauth2 requests sqlalchemy tornado
      traitlets prometheus_client async_generator
    ];
  
    # Disable tests because they take an excessive amount of time to complete.
    doCheck = false;
  
  
    meta = with lib; {
      description = "Serves multiple Jupyter notebook instances";
      homepage = http://jupyter.org/;
  