anchor.diff:        license = licenses.lgpl21Plus;
       };
     };
  -  
  +
     nbconvert = buildPythonPackage rec {
       version = "4.0.0";
       name = "nbconvert-${version}";
  -    
  +
       src = pkgs.fetchurl {
         url = "https://pypi.python.org/packages/source/n/nbconvert/${name}.tar.gz";
         sha256 = "472ad15d1a71f1ef00c4094c11bb93638858fc89fb2c5838b3aa6b67d981b437";
       };
  -    
  +
       buildInputs = with self; [nose];
  -    
  +
       propagatedBuildInputs = with self; [mistune jinja2 pygments traitlets jupyter_core nbformat ipykernel tornado jupyter_client];
  -    
  +
       meta = {
         description = "Converting Jupyter Notebooks";
         homepage = http://jupyter.org/;
         license = licenses.bsd3;
         maintainers = with maintainers; [ fridh ];
  -    }; 
  -  };
  -  
  +    };
  +  };
  +
     nbformat = buildPythonPackage rec {
       version = "4.0.0";
       name = "nbformat-${version}";
  -  
  +
       src = pkgs.fetchurl {
         url = "https://pypi.python.org/packages/source/n/nbformat/${name}.tar.gz";
         sha256 = "daf9b990e96863d120aff123361156a316757757b81a8070eb6945e4a9774b2d";
       };
  -    
  +
       propagatedBuildInputs = with self; [ipython_genutils traitlets jsonschema jupyter_core];
  -    
  +
       meta = {
         description = "The Jupyter Notebook format";
         homepage = "http://jupyter.org/";
  
positive.code:        license = licenses.mit;
       };
    };
    
    pytestrunner = buildPythonPackage rec {
      version = "2.6.2";
      name = "pytest-runner-${version}";
      
      src = pkgs.fetchurl {
        url = "https://pypi.python.org/packages/source/p/pytest-runner/${name}.tar.gz";
        sha256 = "e775a40ee4a3a1d45018b199c44cc20bbe7f3df2dc8882f61465bb4141c78cdb";
      };
      
      buildInputs = with self; [setuptools_scm pytest];
      
      meta = {
        description = "Invoke py.test as distutils command with dependency resolution";
        homepage = https://bitbucket.org/pytest-dev/pytest-runner;
        license = licenses.mit;
      };
      
      # Trying to run tests fails with # RuntimeError: dictionary changed size during iteration
      doCheck = false;
    };
  
negative.code:     };
    };
  
    pandas = let
      inherit (pkgs.stdenv.lib) optional optionalString;
      inherit (pkgs.stdenv) isDarwin;
    in buildPythonPackage rec {
      name = "pandas-0.16.2";
  
      src = pkgs.fetchurl {
  