anchor.diff:      numpy
       packaging
     ]
  -  ++ lib.optionals ( !isPy3k ) [ futures ];
  +  ++ lib.optionals ( isPy27 ) [
  +    futures
  +  ];
   
     checkPhase = ''
       ${python.interpreter} -m unittest discover -s bokeh/tests
  
positive.code: 
    src = fetchPypi {
      inherit pname version;
      sha256 = "c60d38a41a777b8147ee4134e6142cea8026b5eebf48149e370c44689869dce7";
    };
  
    patches = [
  
negative.code: { buildPythonPackage
  , fetchPypi
  , futures
  , isPy27
  , isPyPy
  , jinja2
  , lib
  